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eHam Forums => Amplifiers => Topic started by: AA6CJ on December 22, 2015, 12:58:42 PM



Title: 1500 pep output max
Post by: AA6CJ on December 22, 2015, 12:58:42 PM
Hi all,
On Ssb that's a whole lot less average power out than other modes.  Has anyone tried petitioning the fcc to make it RMS or average power out?
Fred, aa6cj


Title: RE: 1500 pep output max
Post by: REASTON on December 22, 2015, 01:08:03 PM
Hi all,
On Ssb that's a whole lot less average power out than other modes.  Has anyone tried petitioning the fcc to make it RMS or average power out?
Fred, aa6cj

I suspect some hams have but if the FCC wanted hams to have more power they would have done that when they changed the power definition to peak power decades ago.  Some hams in other countries have a lot less.  Don't complain.  The FCC might lower it if attention is directed at the power allowed now.


Title: RE: 1500 pep output max
Post by: W1BR on December 22, 2015, 01:15:40 PM
How is peak power determined? How does it differ from "RMS" power--and what is RMS power and how is it different than average power?


Title: RE: 1500 pep output max
Post by: W8JX on December 22, 2015, 03:02:49 PM
Hi all,
On Ssb that's a whole lot less average power out than other modes.  Has anyone tried petitioning the fcc to make it RMS or average power out?
Fred, aa6cj

I think it is a moot point because there are a lot of hams running more than legal limit under the guise of having a amp with lots of "head room"


Title: RE: 1500 pep output max
Post by: W1QJ on December 22, 2015, 04:06:00 PM
It's all about ERP.


Title: RE: 1500 pep output max
Post by: WA7PRC on December 22, 2015, 05:00:15 PM
It's all about ERP.
That would be Wyatt ERP.  ;)


Title: RE: 1500 pep output max
Post by: N1OD on December 22, 2015, 05:37:41 PM
How is peak power determined? How does it differ from "RMS" power--and what is RMS power and how is it different than average power?


Peak power is calculated using the maximum voltage that an amplifier can deliver into a 50 ohm load.  The RMS voltage of that same power output can be found by multiplying the peak voltage by .707

If you know the RMS voltage you can find the peak voltage by multiplying the RMS voltage by 1.414

Sometimes average power is equated to RMS power, but I don't think that is technically correct.

We didn't always have peak reading measuring equipment, and the RMS voltage was what a typical analog instrument would read.

Google RMS power, or RMS voltage to see it graphically.

Does that answer your question?

Paul N1OD



Title: RE: 1500 pep output max
Post by: AA6CJ on December 22, 2015, 05:56:21 PM
Not really.  The question is whether a petition has been attempted or not.  Appreciate the banter though.


Title: RE: 1500 pep output max
Post by: AA4PB on December 22, 2015, 06:04:18 PM
I think what we are talking about in reference to SSB is not peak power, but peak envelope power (PEP). PEP is the power at the maximum point of the modulation envelope. The relationship of peak and RMS power (.707 and 1.414) only applies to a continuous sine wave and not to the typical voice modulation envelope of a SSB transmitter. A 100W PEP SSB transmitter has the same output at the voice peaks as a 100W CW transmitter or a 100W FM transmitter. A non-PEP wattmeter reads lower on a SSB signal because the meter can't respond fast enough to read the power at the voice peaks.

RMS power by the way, is the amount of power (in an AC waveform) that produces the same amount of heating in a resistance that an equivalent amount of DC power does. 5W DC will heat a resistor to the same temperature as 5W RMS.

On SSB average power varies with the modulation waveform and RMS doesn't really apply. The only thing you can easily measure with common instrumentation is PEP.


Title: RE: 1500 pep output max
Post by: W1BR on December 22, 2015, 06:20:32 PM
[
If you know the RMS voltage you can find the peak voltage by multiplying the RMS voltage by 1.414

Sometimes average power is equated to RMS power, but I don't think that is technically correct.

We didn't always have peak reading measuring equipment, and the RMS voltage was what a typical analog instrument would read.

Google RMS power, or RMS voltage to see it graphically.

Does that answer your question?

Paul N1OD



Nope. I can find no basis that shows "RMS" power exists...
http://www.w8ji.com/amplitude_modulation.htm


Title: RE: 1500 pep output max
Post by: N0GW on December 22, 2015, 09:23:41 PM
Here is the sorta sideways (but reasonable) logic behind the 1500 PEP maximum power limit:

Previous limit was 1000 Watts INPUT power to the final amplifier (plate current time the plate voltage).  This was usually done in Class C for CW and AM modulation.  Remember that the peak input power of a 1000 watt class C amplifier with 100% AM plate modulation is 4000 watts (4 times the unmodulated carrier level.)

A nominal efficiency for a typical class C amplifier is about 75%.  That would mean our 1000 watt input power, 100% modulated AM transmitter would have an output Peak Envelope Power (PEP) of about 3000 watts.

OK,  here is the slightly sideways part of the subject:  Our AM transmitter is double sideband.  It was reasoned that since Single Sideband occupies half the bandwidth of an AM signal, only half the power should be needed for the same signal to noise ratio.  That would be 1500 watts PEP output.  Of course, that is not mathematically correct but we came out ahead compared with what the correct calculation would have provided.  1500 watts output PEP SSB does provide an advantage over a 3000 PEP output AM signal. 


Title: RE: 1500 pep output max
Post by: AA6CJ on December 23, 2015, 04:11:13 AM
I think what we are talking about in reference to SSB is not peak power, but peak envelope power (PEP). PEP is the power at the maximum point of the modulation envelope. The relationship of peak and RMS power (.707 and 1.414) only applies to a continuous sine wave and not to the typical voice modulation envelope of a SSB transmitter. A 100W PEP SSB transmitter has the same output at the voice peaks as a 100W CW transmitter or a 100W FM transmitter. A non-PEP wattmeter reads lower on a SSB signal because the meter can't respond fast enough to read the power at the voice peaks

On SSB average power varies with the modulation waveform and RMS doesn't really apply. The only thing you can easily measure with common instrumentation is PEP.


Cool, this I understand.   they'd have to buy into something like a running average since the power is varying all the time.  Can't hang you hat on efficiency either because that can vary tube to tube and with by class.  I guess I should be happy that cw and rtty pep is steady and by comparison allows for sooo much more output power. (Sounds like I'm a power junkie....). I could see where a digital voice encoding scheme would help, but how would you ever get the traction for that.  I read an article about how we went from AM to SSB, but I doubt it would be as easy, and that was hard.  Probably much harder.


Title: RE: 1500 pep output max
Post by: KG4RUL on December 23, 2015, 06:17:21 AM
It's all about ERP.
That would be Wyatt ERP.  ;)

Earp


Title: RE: 1500 pep output max
Post by: SM0AOM on December 23, 2015, 08:38:56 AM
Here is the sorta sideways (but reasonable) logic behind the 1500 PEP maximum power limit:

Previous limit was 1000 Watts INPUT power to the final amplifier (plate current time the plate voltage).  This was usually done in Class C for CW and AM modulation.  Remember that the peak input power of a 1000 watt class C amplifier with 100% AM plate modulation is 4000 watts (4 times the unmodulated carrier level.)

A nominal efficiency for a typical class C amplifier is about 75%.  That would mean our 1000 watt input power, 100% modulated AM transmitter would have an output Peak Envelope Power (PEP) of about 3000 watts.

OK,  here is the slightly sideways part of the subject:  Our AM transmitter is double sideband.  It was reasoned that since Single Sideband occupies half the bandwidth of an AM signal, only half the power should be needed for the same signal to noise ratio.  That would be 1500 watts PEP output.  Of course, that is not mathematically correct but we came out ahead compared with what the correct calculation would have provided.  1500 watts output PEP SSB does provide an advantage over a 3000 PEP output AM signal. 

I would say that the FCC applied some precedents from the professional world.

Since long ago, the power limits applied to smaller SSB stations in the mobile services on HF have been in the range of 1000 to 1500 W PEP,
A ship station for HF is subject to a limit of 1500W if operated on the high-seas HF bands and to 400W on the MF coastal telephony bands. 
This was in turn derived from the AM power levels common in the pre-SSB era, which usually were in the order of 300 to 500 W carrier, which could provide about 1200-2000 W PEP output at 100% modulation.

An amateur station was considered to be in "the same league" as a ship station.



Title: RE: 1500 pep output max
Post by: K6BRN on December 23, 2015, 10:02:07 AM
Putting RMS vs. peak power into perspective....

A continuous tone on SSB with a PEP of 1500 watts will provide an RMS output of 750 watts, which is "3 db"  "less", so it would take 3 KW PEP to achieve 1500 watts RMS with a single tone..

This is only 1/2 s-unit improvement (relative to a single tone) with a major increase in amplifier mass and cost and major improvements needed to most antenna systems.  And the near-field RF danger will increase as will stray RF problems, so shack grounding and stand-off distances become even more critical.

Considering that some countries have a 400 watt limit (UK, Australia) and our close neighbor (Canada) at 2.25 KW - only 1/4 of an S-unit higher - we are doing OK.

Brian K6BRN


Title: RE: 1500 pep output max
Post by: NO2A on December 23, 2015, 10:26:20 AM
The F.C.C. already gave us a break. The power limitation used to be for input power, not output. In some countries the Novice License equivalent might be 10 watts. (No offense to the QRP crowd. )


Title: RE: 1500 pep output max
Post by: SM0AOM on December 23, 2015, 10:46:06 AM
Putting RMS vs. peak power into perspective....

A continuous tone on SSB with a PEP of 1500 watts will provide an RMS output of 750 watts, which is "3 db"  "less", so it would take 3 KW PEP to achieve 1500 watts RMS with a single tone..

This is only 1/2 s-unit improvement (relative to a single tone) with a major increase in amplifier mass and cost and major improvements needed to most antenna systems.  And the near-field RF danger will increase as will stray RF problems, so shack grounding and stand-off distances become even more critical.

Considering that some countries have a 400 watt limit (UK, Australia) and our close neighbor (Canada) at 2.25 KW - only 1/4 of an S-unit higher - we are doing OK.

Brian K6BRN

This contains two misconceptions;
first there is no such thing as "RMS Power",
and second a continuous single AF tone modulating an SSB transmitter results in a
constant-envelope waveform with a peak to average power ratio of unity, or average power = PEP.

This is known by every RF engineer.
 


Title: RE: 1500 pep output max
Post by: WB2WIK on December 23, 2015, 11:18:27 AM
The F.C.C. already gave us a break. The power limitation used to be for input power, not output. In some countries the Novice License equivalent might be 10 watts. (No offense to the QRP crowd. )

I agree.  Our output power limitation here in the U.S. is very liberal and only a few places in the world allow any more; many places allow quite a lot less.

It would be cool if we could run more power on 30m, though.  Some places can.



Title: RE: 1500 pep output max
Post by: AA4PB on December 23, 2015, 11:27:09 AM
RMS power is sometimes used in the rating of amplifiers in the audio industry. It is the resistance of the load times the square of the RMS current.


Title: RE: 1500 pep output max
Post by: KB8E on December 23, 2015, 12:18:04 PM
There is such a thing as rms power, it just doesn't have any significance in the real world. Consider a sinusoidal voltage of V = 170 sin (2*pi*60*t). The average voltage is zero (no DC component). The peak voltage is 170 V. The rms voltage is found by squaring the voltage waveform, averaging over an integer number of complete cycles, and then taking the square root. The result for the above waveform is 120 V. The waveform for instantaneous power is found by taking the voltage waveform, squaring it and dividing by the load resistance. For a load of 144 ohms for example, we get a waveform of P = 200 sin(2*pi*60*t)*sin(2*pi*60*t). The average is 100 W. The peak is 200 W. The rms is 158 W.

Sam


Title: RE: 1500 pep output max
Post by: K6UJ on December 23, 2015, 08:07:01 PM
It's all about ERP.
That would be Wyatt ERP.  ;)


I love it !!    :D :D :D :D :D :D :D :D :D
Good one Bryan !!

73,
Bob
K6UJ


Title: RE: 1500 pep output max
Post by: N0GW on December 23, 2015, 08:27:24 PM
"There is such a thing as rms power, it just doesn't have any significance in the real world. Consider a sinusoidal voltage of V = 170 sin (2*pi*60*t). The average voltage is zero (no DC component). The peak voltage is 170 V. The rms voltage is found by squaring the voltage waveform, averaging over an integer number of complete cycles, and then taking the square root. The result for the above waveform is 120 V. The waveform for instantaneous power is found by taking the voltage waveform, squaring it and dividing by the load resistance. For a load of 144 ohms for example, we get a waveform of P = 200 sin(2*pi*60*t)*sin(2*pi*60*t). The average is 100 W. The peak is 200 W. The rms is 158 W. "

Sam, you seem to be confusing two different concepts in your presentation.  When measuring the power of an RF signal with an oscilliscope you do, in fact, see peak voltage, not RMS voltage.  Of course, to calculate the power of the RF signal, you do have to multiply the voltage by 0.707 (1 over the square root of 2) to get the RMS voltage of that sine wave.  That is what we use to calculate our 1500 watts of RF.  The FCC 1500 watt output power is true watts.   By true, I mean that 1500 watts has the same heating effect on a resistor as 1500 watts of DC power.

When we apply the term Peak Envelope Power, we are talking about the true RF power at the peak of our modulated RF signal.  Our SSB signals vary between zero power and some maximum depending upon our applied audio waveforms.  Whatever that maximum is we call the Peak Envelope Power.  That is to say that if we look at the signal waveform with an oscilloscope, we would see a voltage peak 1.414 times the RMS or DC equivalent of that power.  We are already taking all that into account.

Is that making sense?

Gary


Title: RE: 1500 pep output max
Post by: KB8E on December 24, 2015, 02:30:56 AM
Gary,

My understanding is that we're talking about a regulatory limit of 1500 watts PEP. I interpret that to mean an instantaneous maximum power of 1500 watts. When observing the voltage waveform on an oscilloscope, this would occur at the peak of the RF envelope and would be equal to the peak voltage squared divided by the load resistance. This would also be the peak 'heating' power. The troughs of the envelope where the RF waveform is zero represent zero power. If one is able to determine the rms value of the RF voltage waveform, that value can be squared and divided by thr load resistance to get average power output. Due to time constants in a real load, this heat is what would be observed as heat in a dummy load.

Sam



Title: RE: 1500 pep output max
Post by: K6BRN on December 24, 2015, 06:54:30 AM
To SM0AOM:

(Sigh!)  Really?  Did you read the OP and understand the context of my reply?  He asked about Peak vs. RMS power limits, and I replied in kind.

RMS power can be easily calculated for any single tone (by definition a sinusoidal waveform), from 50 Hz AC to microwave and beyond and is a valid metric for power comparisons.

A single tone is defined as a pure sinusoid at any frequency, mechanical or electrical, however it is derived.  It will appear as a single spectral line on an analyzer - no side lobes, no width.   How a reasonable facsimile might be produced - i.e. single constant amplitude audio tone injected into an SSB modulator to produce CW, is not really important, except that the OP was asking the question in terms of SSB.

The OP asked about moving from a 1500 watt peak SSB power output limit to a 1500 watts RMS limit.  Did you really expect a long lecture on "Average Power"?  My answer, qualified in terms of single tones, a context under which the OPs question is easily understood and answered, was simply that the real world performance difference is not that great and the relative cost is high - a lot of effort for a small gain.   That was my point.

So... what's the problem?

Brian  K6BRN


Title: RE: 1500 pep output max
Post by: K7EXJ on December 24, 2015, 07:40:22 AM
It's all about ERP.
That would be Wyatt ERP.  ;)


I love it !!    :D :D :D :D :D :D :D :D :D
Good one Bryan !!

73,
Bob
K6UJ
Urp! ('Scuse) :D


Title: RE: 1500 pep output max
Post by: K6BRN on December 24, 2015, 10:45:20 AM
Craig:  Prilosec works wonders for indigestion.

Gary:  Agree with your comments ...  exept that RMS voltage is the mathematically handy fiction - you'll never see it on an oscilloscope - unless its a flat DC trace.

RMS power, calculated from the scaled peak voltage of a sinusoid and the load resistance, will measure as true power with an RF bolometer. 

BTW - RMS power was used as the sole legal definition of audio amplifier power output during the 70's, when false amplifier power claims based on arbitrary metrics were out of control and the government stepped in.

Brian K6BRN


Title: RE: 1500 pep output max
Post by: N0GW on December 24, 2015, 01:24:46 PM
"Gary:  Agree with your comments ...  exept that RMS voltage is the mathematically handy fiction - you'll never see it on an oscilloscope - unless its a flat DC trace.

RMS power, calculated from the scaled peak voltage of a sinusoid and the load resistance, will measure as true power with an RF bolometer. "

No argument from me.  If my words did not indicate that, I apologize.  My intent was to emphasize that with sine wave power measurement, we do use the concept of RMS.  This term has a very specific meaning in engineering that allows us to describe what true heating value is of any arbitrary voltage waveform.  For sine waves, the RMS (Root Mean Square) value works out nicely to have a square root of two relationship between peak voltage and the RMS heating (DC) equivalent value.  Other waveforms have different relationships.

The confusion in this discussion is Sam's assumption that the FCC 1500 watt PEP power limit is based upon the peak voltage of the RF sine wave waveform and not the RMS heating value of the RF.  Of course, all the FCC cares about it the equivalent heating value in watts.  Of course, I'd use something a little beefier than my bolometer element for this measurement.

There may be another confusion in this.  We have all seen diagrams of the Christmas Tree oscilloscope trace of our voice modulated SSB transmitted signal.  I hope everyone understands that the term Peak Envelope Power (PEP) refers to the RMS RF power at the highest points in the trace.  With our typical 100 watt output SSB transceivers, the highest points are at the 100 watt RMS power level.  That is defined as 100 watts PEP.  With voice modulation, the average power output of that transceiver with voice is typically only 20% or 30% of that 100 watt PEP signal.  While there were arguments in the 1980s when the change from final amplifier input power to the present output power limit about using average power versus PEP, the PEP won on technical points.  (When measuring average power, what time constant do you use for the averaging? 100 milliseconds?  1 second? 1 day?  PEP avoids that issue.)

Gary - N0GW



Title: RE: 1500 pep output max
Post by: KM1H on December 24, 2015, 06:36:21 PM
RMS power is an invention of the audiophools and now some technically challenged hams have picked up the new buzzword.

Even JI agrees ::)
http://www.w8ji.com/amplitude_modulation.htm

Sort of reminds me of Sears, Harbor Freight, and other frauds when rating compressor HP, generator power, etc.
Or the BHP rating of the bad old muscle car days.

Someone in marketing will always find a new gimmick to skin the consumer.

Here is some interesting reading to digest, I havent gone thru it all yet.
http://www.audioholics.com/audio-amplifier/amplifier-power-ratings


Title: RE: 1500 pep output max
Post by: N0GW on December 24, 2015, 07:19:27 PM
"RMS power is an invention of the audiophools and now some technically challenged hams have picked up the new buzzword."

OK, I guess I was getting carried away with my terminology.  I was trying to get across that the PEP power we are discussing is based upon RMS voltage and RMS current.  I apologize for the confusion on that detail.

I'll say it definitively: The term RMS power is incorrect.  There is RMS voltage and RMS current but when we discuss power, it is simply power.  We can talk about peak power, average power, or even Peak Envelope Power.  Power is exactly true heating power when we are discussing RF power.

Gary - N0GW


Title: RE: 1500 pep output max
Post by: SM0AOM on December 24, 2015, 11:45:24 PM
The concept of RF power is considered sufficiently important by the international community to warrant its own definitions in the ITU Radio Regulations, which usually have been carried over verbatim into national rules;

"1.156     power: Whenever the power of a radio transmitter, etc. is referred to it shall be expressed in one of the following forms, according to the class of emission, using the arbitrary symbols indicated:

- peak envelope power (PX or pX);

- mean power (PY or pY);

- carrier power (PZ or pZ).

For different classes of emission, the relationships between peak envelope power, mean power and carrier power, under the conditions of normal operation and of no modulation, are contained in ITU-R Recommendations which may be used as a guide.

For use in formulae, the symbol p denotes power expressed in watts and the symbol P denotes power expressed in decibels relative to a reference level.

1.157     peak envelope power (of a radio transmitter): The average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope taken under normal operating conditions.

1.158     mean power (of a radio transmitter): The average power supplied to the antenna transmission line by a transmitter during an interval of time sufficiently long compared with the lowest frequency encountered in the modulation taken under normal operating conditions.

1.159     carrier power (of a radio transmitter): The average power supplied to the antenna transmission line by a transmitter during
one radio frequency cycle taken under the condition of no modulation."


Note that there are no references to "RMS Power" here, nor in any radio engineering texts.

If the power limits should be expressed in mean power the question of the proper time constant to use would arise. In the previous regime of specifying maximum indicated input power, the FCC (and other Administrations) prescribed an allowed maximum time constant of 0,25 s for the plate meter when expressing current readings in SSB transmitters.

Up to two years ago, the Swedish Power limits were expressed as an undefined "maximum power" of 1000W.
There was no guidance in the rules how this was defined or should be measured, in contrast to other Administrations that used the ITU definitions.




Title: RE: 1500 pep output max
Post by: K7KBN on December 25, 2015, 11:30:56 AM
"RMS power is an invention of the audiophools and now some technically challenged hams have picked up the new buzzword."

OK, I guess I was getting carried away with my terminology.  I was trying to get across that the PEP power we are discussing is based upon RMS voltage and RMS current.  I apologize for the confusion on that detail.

I'll say it definitively: The term RMS power is incorrect.  There is RMS voltage and RMS current but when we discuss power, it is simply power.  We can talk about peak power, average power, or even Peak Envelope Power.  Power is exactly true heating power when we are discussing RF power.

Gary - N0GW

As I was told by a Radio Shack clerk back around 1970 (shortly after the FTC laid down the requirements for how audio equipment power "shall" be rated):

"RMS?  That stands for 'Real Music Sound'"!


Title: RE: 1500 pep output max
Post by: AA6CJ on December 25, 2015, 01:16:04 PM
I think we are at the gist of it now.  Had I been aware of the ITU language, I would have asked the question to say has anyone petitioned the fcc to make the power level based on mean power.  The question is to address that the average power is 20-30% under pep.  I apologize if I started us down the rabbit hole not being sure whether I should refer to it as average or rms power.  My bad. 


Going back to my question, I wonder if one could measure mean power properly for ssb?  And, .25s doesn't "feel" like a long enough interval.


Title: RE: 1500 pep output max
Post by: REASTON on December 25, 2015, 01:25:47 PM
I think we are at the gist of it now.  Had I been aware of the ITU language, I would have asked the question to say has anyone petitioned the fcc to make the power level based on mean power.  The question is to address that the average power is 20-30% under pep.  I apologize if I started us down the rabbit hole not being sure whether I should refer to it as average or rms power.  My bad.  


Going back to my question, I wonder if one could measure mean  power properly for ssb?  And, .25s doesn't "feel" like a long enough interval.

Mean or average power in reference to SSB doesn't work as a good way to measure output power because it is dependent upon the characteristics of an individuals voice. Not easy to measure.  Peak power is not easy to measure with much accuracy either.  The FCC probably should have just left the old way of measuring power in place because it was simpler and only common cheap metering needed to be used to measure average input for SSB.  


Title: RE: 1500 pep output max
Post by: AA6CJ on December 25, 2015, 01:43:26 PM
thanks

I will work on the audio side to maximize my signal mean power without it sounding horrible.  Wouldn't know what could be said to fcc to replace that we have.  Great for cw and rtty though having 1500 pep.


Title: RE: 1500 pep output max
Post by: KM1H on December 25, 2015, 02:31:25 PM
Quote
Up to two years ago, the Swedish Power limits were expressed as an undefined "maximum power" of 1000W.
There was no guidance in the rules how this was defined or should be measured, in contrast to other Administrations that used the ITU defintions.

Sounds smart to me, let a sleeping dog lie as the old saying goes which might go back to the Egyptians of old.

Carl


Title: RE: 1500 pep output max
Post by: G3RZP on December 25, 2015, 02:55:29 PM
Quite how it got done but here we got the power limit of 400 watts PEP (or whatever - it's band dependent) at the antenna. As I understand it, that was because of the argument that at V/U HF, transmission line loss needed overcoming.

Now with an antenna feedpoint impedance on 160 of something like 1200 + j550, the chances of measuring power at the antenna to any degree of accuracy are pretty remote....

Fortunately, with budgetary constraints being what they are, unless there's a problem, the administrations don't bother too much these days unless there's a problem.


Title: RE: 1500 pep output max
Post by: W9IQ on December 29, 2015, 01:50:41 PM
I think the FCC General Class question pool expresses the measurement technique quite simply:

Quote
What is the output PEP from a transmitter if an oscilloscope measures 200 volts peak-to-peak across a 50 ohm dummy load connected to the transmitter output?
B. 100 watts

Take note that this is using the maximum attained RMS voltage of the modulated carrier - which is essentially a sine wave.

In practice, a PEP meter is simple to fabricate. A peak envelope voltage detection circuit (< $2 USD) makes quick work of the measurement if one assumes a 50 ohm load. Take the peak envelope voltage value, square it, then multiply by 0.0025 and you have the PEP (peak envelope power). A $2 USD PIC processor can do the math and drive the display. No need to worry about time averaging or any of the hand wringing issues raised in this thread. And the best part is you don't have to try to interpret bouncing needles or rapidly changing digital displays.


- Glenn W9IQ


Title: RE: 1500 pep output max
Post by: KK4YDR on December 29, 2015, 05:38:49 PM
It's all about ERP.

Bingo!!

Effective Radiated Power can make that 1500 watts seem like 5000 watts depending on how well designed, constructed, and efficient your antenna system is.

Using this calculator, assuming all background mathematics is correct, http://www.csgnetwork.com/antennaecalc.html (http://www.csgnetwork.com/antennaecalc.html)

at 1500 watts with a 2.1dBd (As in dB(dipole)) in gain should net me around 4600 watts effective power. That is an amazing amount of focused power over a unity (0dBd) gain dipole antenna. So in essence a flat top conventional dipole antenna, having a unity gain, should have an ERP of 1:1 meaning 1000 watts in 1000 watts out. Of course this is not representative of feed line losses or other inefficiencies i.e. insertion losses from different toys that you put on your antenna system.

Since I actually only transmit at 100 watts through my ladder line fed antenna with absolutely minimal feedline loss (Cheer for 450 ohm woohoo) I should be putting out 270 watts ERP or roughly another S unit or so extra over barefoot 100w.

I like to measure my numbers for ERP via dBd because it gives me a real source of comparison and something tangible since no on really has a Isotropic point of reference as in dBi. But this is all just my opinion.

Lastly a Yagi for instance measured typically in dBi due to their usually being mounted way atop a tower, in this example lets say a 20 meter Yagi measured around 14dBi with 100 watts fed to it will have an ERP in excess of 2.5KW, That is why so many amateurs bite at the bit to get a tower and a Yagi airborne. They are that good :p

My point of reference is my 80meter horizontal loop about 65' off Earth at all points fed with 450 ohm window line.



Title: RE: 1500 pep output max
Post by: NO2A on December 29, 2015, 09:14:51 PM
It's all about ERP.
Likewise, 1500 watts into a 160m hamstick (if it could handle it which it can't )would still be -0db gain.


Title: RE: 1500 pep output max
Post by: KM3F on December 29, 2015, 11:14:13 PM
2500 watts peak at the output jack.
How much it takes to produce this has no bearing.
Envelope is the top of the output wave form no matter what the shape is below the peak.
How many rms, goats, pigs,  chickens etc watts below the peak makes no difference in reference to the  'rule'.
ERP is independent because it's what you do with the 1500 watts peaks after the output jack, at the ant and direction that makes up the ERP.
The effects of the  1500 watt limit can be enhanced under the peak power by increasing the average under the peak in an amplitude voice mode.
This can be done by using compression methods to raised the average under the peak, rule.
.
In CW, you have no opportunity to do this because the peak is always what is present with the carrier keyed  on.
The only difference is the repetition rate has an average power but it's effects are not the same as varying  voice averages.
The main effect of increased keying speed is to raise the power consumed by the amplifier the faster the repetition rate becomes making it look more like an AM modulation of the total power because it still has the same peak power as  AM drive signal has but has near straight sides to the signal instead of varying shape voice irregular  wave type of drive signal.
The effects of ERP are still available in all modes because it's still a function of what you do with the power 'after' it leaves the amplifier.
The PEP  rule is tough to get around but it does allow you to increase the average in a voice modes that would be harder to regulate and measure as a DC input unless instrumentation is used like we have for RF.
In AM mode, the carrier is the reference point. At 375 watts max carrier times 4 for 100 % modulation = 1500 watts.
You can still raised the average under the peak and get the same benefit result  for signal as SSB except for less efficient and wasted  side band power.
But  the rules don't address that.
Good luck.



Title: RE: 1500 pep output max
Post by: KM3F on December 29, 2015, 11:23:55 PM
The  only instance I can come up with for ERP as the rule is the 5 channels on 60 meters.
That is done for a totally different purpose to limit QRM to other services in the same band as well as the frequency and bandwidth has to be precision to specified  limits.
Good luck.


Title: RE: 1500 pep output max
Post by: G3RZP on December 30, 2015, 02:46:04 AM
About 20 years ago, in European standards and regulatory requirements, ERP was used below 1 GHz and EIRP above, on the basis that a horn antenna can have the gain over isotropic accurately determined by the physical dimensions and so measurement was likely to be more accurate. The difference between ERP and EIRP is defined as 2.16dB. Now recently the ITU seem to have been persuaded that for the new 472kHz and 5 MHz allocations, the power limit should be EIRP - possibly at the insistence of the Russians who were against those allocations anyway. Actually measuring radiated power with accuracy is not an easy task, anyway, especially if you don't have a calibrated antenna range and are working at HF - above 300 or so MHz, using a fully anechoic chamber makes life a bit easier.


Title: RE: 1500 pep output max
Post by: SM0AOM on December 30, 2015, 03:39:56 AM
About 20 years ago, in European standards and regulatory requirements, ERP was used below 1 GHz and EIRP above, on the basis that a horn antenna can have the gain over isotropic accurately determined by the physical dimensions and so measurement was likely to be more accurate. The difference between ERP and EIRP is defined as 2.16dB. Now recently the ITU seem to have been persuaded that for the new 472kHz and 5 MHz allocations, the power limit should be EIRP - possibly at the insistence of the Russians who were against those allocations anyway. Actually measuring radiated power with accuracy is not an easy task, anyway, especially if you don't have a calibrated antenna range and are working at HF - above 300 or so MHz, using a fully anechoic chamber makes life a bit easier.

To accurately determine actual radiated power, antenna efficiency and ERP in the HF range it takes a helicopter with a field-strength meter with a data logger and some quite special software (and a large budget). Back in the days when there was a market for MF and HF broadcast antennas this was often done for contractual purposes.

The reasons for use of EIRP in the 5 MHz case is that most current HF circuit and interference prediction software use EIRP as one input parameter.


Title: RE: 1500 pep output max
Post by: W9IQ on December 30, 2015, 02:50:06 PM
To the OP's question, PEP is the easiest to measure so I would not ask the FCC for any changes.

Glenn W9IQ


Title: RE: 1500 pep output max
Post by: AA6CJ on December 30, 2015, 03:03:24 PM
That's the message that I copied.  Hi.
73 thanks for the interesting and educational discussion.
Fred, aa6cj


Title: RE: 1500 pep output max
Post by: K6UJ on December 31, 2015, 04:49:16 PM
I think we are at the gist of it now.  Had I been aware of the ITU language, I would have asked the question to say has anyone petitioned the fcc to make the power level based on mean power.  The question is to address that the average power is 20-30% under pep.  I apologize if I started us down the rabbit hole not being sure whether I should refer to it as average or rms power.  My bad.  


Going back to my question, I wonder if one could measure mean  power properly for ssb?  And, .25s doesn't "feel" like a long enough interval.

Mean or average power in reference to SSB doesn't work as a good way to measure output power because it is dependent upon the characteristics of an individuals voice. Not easy to measure.  Peak power is not easy to measure with much accuracy either.  The FCC probably should have just left the old way of measuring power in place because it was simpler and only common cheap metering needed to be used to measure average input for SSB.  
[/quote

The FCC doesn't base their decisions on what's simpler or cheaper.
:-) :-).   
Bob
K6UJ


Title: RE: 1500 pep output max
Post by: KK4YDR on December 31, 2015, 04:51:20 PM
The  only instance I can come up with for ERP as the rule is the 5 channels on 60 meters.
That is done for a totally different purpose to limit QRM to other services in the same band as well as the frequency and bandwidth has to be precision to specified  limits.
Good luck.

Yeah i'm quite sure if they didn't limit ERP and wen't with pep there would be split splatter all over the place. The band would look like someone is frying water in oil. Hell 80 meters looks like this all the time.


Title: RE: 1500 pep output max
Post by: W9IQ on December 31, 2015, 05:36:27 PM
PEP is easy to measure. See my earlier post in this thread.

Average power for SSB could be measured but it would take a fast enough processor and a more rigorous definition for average power.

- Glenn W9IQ


Title: RE: 1500 pep output max
Post by: AA6CJ on January 01, 2016, 06:06:07 AM
Yeah, that get us back to what time interval to average across.  How do you get consensus on that?  Assuming Ssb is ultimately replaced by a digital voice waveform, that waveform pep might be like rtty and cw.


Title: RE: 1500 pep output max
Post by: W9IQ on January 01, 2016, 06:16:06 AM
Since our Amateur Radio community is sadly lacking in standards, I don't expect concensus on average power to be imminent. Consider that S meter "standard" is only a techical recommendation and look how poorly that is followed.

Also consider that their are dozens of modulation modes that would need to be addressed.

That is why I like PEP - clearly defined and simple to measure regardless of the modulation mode.

- Glenn W9IQ


Title: RE: 1500 pep output max
Post by: SM0AOM on January 01, 2016, 06:28:04 AM
Yeah, that get us back to what time interval to average across.  How do you get consensus on that?  Assuming Ssb is ultimately replaced by a digital voice waveform, that waveform pep might be like rtty and cw.

It is highly unlikely that a vocoder and a channel coder good enough to get a telephone quality DV data stream into a constant-envelope RF waveform suitable for transmission on HF will surface in the forseeable future.

Current DV technology for HF channels needs a 2400-3600 bps channel capacity, and this takes a multitone or PSK/QAM modem to achieve this throughput. These modems use a waveform that has a peak-to-average ratio which is about the same as SSB voice, and since distorsion is a critical parameter PEP will still be the most suitable power measure.

It may very well be that the end of amateur radio comes before the end of analog SSB.


Title: RE: 1500 pep output max
Post by: AA6CJ on January 01, 2016, 04:05:33 PM
Thanks, the average power might be the same, but aren't all the QAM tones sent out at full pep? 

If you averaged the power out of cw you'd be counting the time between the dits and dahs. 

OM I'm listening...got my attention with the digital waveform....   :D

We may all die off before ssb's demise but hopefully not HR.  I read recently how big a deal it was to switch from am to Ssb.


Title: RE: 1500 pep output max
Post by: SM0AOM on January 02, 2016, 12:58:39 AM
QAM is one method to approach the Shannon limit in a modulated waveform, and the more noise-like the waveform is, the closer to this limit you are getting. White noise has a long term peak-to-average ratio of about 13 dB, so to use a power amplifier efficiently it is necessary to use some processing in the time domain, frequency domain or both. The goal is to reduce the peak-to-average ratio without introducing undue distorsion.

Each carrier in a multitone or OFDM modem can be modulated in different ways, ranging from FSK to multilevel QAM,but all have in common that they may add in phase which may create a very high peak-to-average ratio. This is avoided by various forms of processing. The PEP in unprocessed waveforms can be very high compared to the average power, and this is unfavourable in peak power and distorsion limited transmitter, which most practical systems contain.

CW or Morse can use any averaging time desired, but with long averaging times, such as minutes, hours or days, we end up in impractical relations between peak and average power. Intra-character spaces and listenng pauses would then enter the pricture.

A practical approach that I believe is used almost universally is to average the power reading for Morse transmissions over a time interval equal to the length of the shortest signalling element used. This would take into account dynamic electrical and thermal stresses of the output devices. For evaulating thermal stresses in the power supply or the cooling system, longer averaging times, up to several minutes, may be appropriate.


Title: RE: 1500 pep output max
Post by: AA6CJ on January 02, 2016, 04:47:45 PM
If all of the points of the constellation of QAM are sent at the same amplitude, then wouldn't that amplitude be 1500 pep? 

I've read that the average power of Ssb is actually 20-30 percent of Pep because of variations in voice sound level at various frequencies as we speak.  You are way way beyond me in understanding, I'm just trying to understand how we could get more power for  ssb contesting.  I guess I envy the power of cw and rtty that is allowed because they are binary. 0 or 1500 watts.  Voice is far from that.  I originally thought that we could address this by looking at it from an average power perspective.  Not a good idea based on the technical challenges of measuring it as discussed in the thread.

Digital voice is really as a side thought, but one I'm interested in.


Title: RE: 1500 pep output max
Post by: KM1H on January 02, 2016, 07:57:50 PM
Quote
I've read that the average power of Ssb is actually 20-30 percent of Pep because of variations in voice sound level at various frequencies as we speak.


That is without any processing which can raise it to 50% and still sound good.

Quote
I'm just trying to understand how we could get more power for  ssb contesting.

Crank up the processor until your taking out 5-10 kHz and eliminating interlopers. That is the prime directive of contesting these days as it not only raises your average power to almost PEP but you win the game of bumper cars or mines bigger ::)

Carl

 


Title: RE: 1500 pep output max
Post by: W6RZ on January 02, 2016, 09:42:31 PM
If all of the points of the constellation of QAM are sent at the same amplitude, then wouldn't that amplitude be 1500 pep?

You're probably thinking of QPSK, where the four constellation points are at the same power level. But you can't send the raw symbols, it would take way too much bandwidth. You have to filter the symbols to limit the bandwidth, and the typical filter for QPSK (and QAM) is the root raised cosine filter.

The roll-off factor of the RRC filter determines the PAPR level. For the 0.35 roll-off that's used on DVB-S, the PAPR is around 4.5 dB. Sharper roll-offs increase the PAPR.

Here's a 100 tap RRC at 0.35 roll-off. Symbol rate is 12 Msyms/s and the bandwidth is 16.2 MHz.

(http://www.w6rz.net/qpskrrc.png)


Title: RE: 1500 pep output max
Post by: AA6CJ on January 03, 2016, 07:58:30 AM

Quote
You're probably thinking of QPSK, where the four constellation points are at the same power level. But you can't send the raw symbols, it would take way too much bandwidth.

That's exactly what I was assuming.  Thanks for taking the time to explain it.  The light bulb came on....


Title: RE: 1500 pep output max
Post by: AA6CJ on January 03, 2016, 08:07:29 AM
Quote
I've read that the average power of Ssb is actually 20-30 percent of Pep because of variations in voice sound level at various frequencies as we speak.


That is without any processing which can raise it to 50% and still sound good.

Quote
I'm just trying to understand how we could get more power for  ssb contesting.

Crank up the processor until your taking out 5-10 kHz and eliminating interlopers. That is the prime directive of contesting these days as it not only raises your average power to almost PEP but you win the game of bumper cars or mines bigger ::)

Carl

 


Carl I think you've nailed it here.  K9EID, has started doing a series on audio articulation.  Limiting the audio to those frequencies that convey through articulation and then applying some compression or limiting the pep peaks judiciously on top of that might be the secret sauce.  But already what you describe is 3db, and according to a contest university presentation I watched recently, each dB increases score by 6%!

thanks OM,
Fred


Title: RE: 1500 pep output max
Post by: WB4JTR on January 03, 2016, 03:11:43 PM
Putting RMS vs. peak power into perspective....

A continuous tone on SSB with a PEP of 1500 watts will provide an RMS output of 750 watts, which is "3 db"  "less", so it would take 3 KW PEP to achieve 1500 watts RMS with a single tone...


Brian K6BRN

Not true.  Remember, PEP is defined as the RMS [ed- " RMS-based"] power at the peak of the envelope.  So a single tone from a 1500W SSB transmitter is 1500W (by RMS).


Title: RE: 1500 pep output max
Post by: KM1H on January 05, 2016, 05:22:38 PM
Here we go again with an audiophool version of reality....Im not saying your one but that version grew fast wings from them


Title: RE: 1500 pep output max
Post by: WB4JTR on January 11, 2016, 05:55:03 PM
Audiophool version of reality based on waveform shape has no place in RF linear amplifiers.  RF power is always expressed as RMS [ed- "RMS based"] because the [RF] waveform is always sinusoidal.  The FCC demands it by limiting harmonic content.  So PEP is simply RMS [ed- "RMS based"] power in the single highest-amplitude sinusoid contained within the signal envelope.


Title: RE: 1500 pep output max
Post by: KM1H on January 12, 2016, 12:01:07 PM
Wow! You probably believe the earth is flat also.

How about coming up with the FCC citation to support your "theory"?


Title: RE: 1500 pep output max
Post by: KM3F on January 12, 2016, 04:01:10 PM
Visit this web  address            www.eznec.com/Amateur/RMS_Power.pdf.
There you will find that RMS power can be calculated as a Math function only, and has no use or value in terms of RF POWER.
Be sure you keep repeating wave forms separate from random waveforms such as voice because they must be treated differently in terms of RF power.
A random wave form such as voice modulation cannot be practically represented by anything more the  Peak values or Average values, for power into a Load.
This is why good RF power meters offer Peak and average functions.
Look at the pdf to find out why.

Good luck..


Title: RE: 1500 pep output max
Post by: W5HRO on January 13, 2016, 05:40:04 PM
Looks like another one of those Extra Class CB'ers  ::)  They are all over...


Title: RE: 1500 pep output max
Post by: K4KYV on January 13, 2016, 08:17:48 PM
There is no such thing as "RMS power".  Average or mean power is what you get when you multiply RMS voltage times RMS current. Average voltage times average current results in a physically meaningless quantity. Nevertheless the term RMS power is widely but incorrectly used within the audiophool community.

Even the term "average voltage" and "average current" must be qualified.  The average voltage or current value of a sine wave or any other unrectified a.c. waveform is inherently zero, since one half cycle is positive with respect to base line while the other half cycle is negative.  A precise description would be the average (or mean) of the absolute value of  voltage or current of the a.c. waveform.


Title: RE: 1500 pep output max
Post by: K4KYV on January 14, 2016, 07:24:10 AM
Popular Hammy Hambone "wattmeters", including the highly extolled Bird 43, don't measure power at all; they are RF voltmeters, with a scale calibrated to read watts into an accurately-known purely resistive load. Using a diode to rectify the RF, they feed the rectified voltage a DC meter, reading absolute-value based average voltage, not true RMS. With a steady carrier source like FM or key-down CW they read correctly, but with a varying-amplitude signal like AM, SSB, pulse and certain digital modes, average voltage is not the same as RMS, and the meter tends to read low. That's why a Bird 43 set to read average power indicates so little power with SSB.  The most widely available true-RMS reading instrument is the thermocouple RF ammeter, but those are very sluggish and don't respond well to rapid peaks. So-called "peak reading" wattmeters are merely average-reading diode rectifier voltmeters with an electronic "hang" circuit, to hold short RF voltage peaks long enough to produce a meter indication. Even those are of questionable accuracy, since they may not fully capture every short-duration peak.  Peak readings can be observed with good accuracy using a calibrated oscilloscope set to monitor the RF envelope pattern.

That was one problem the FCC cited for not using average or mean power as the standard for legal limit.  But to-day, true RMS-reading rf voltage sensors and therefore true average power reading meters are available. These are still diode-rectifier RF voltmeters but which use more complex electronics than the simple hang circuit used for peak readings.  One example is the Bird APM-16 average-reading power meter described here:

http://www.birdrf.com/Products/Wattmeters_Line%20Sections/PortableWattmeters/APM-16_Average-Reading-Power-Meter.aspx

The manual for the APM-16 can be viewed at
http://www.repeater-builder.com/test-equipment/bird/pdf/bird-apm16-im.pdf


Title: RE: 1500 pep output max
Post by: WB4JTR on January 14, 2016, 09:05:02 AM
Wow! You probably believe the earth is flat also.

How about coming up with the FCC citation to support your "theory"?

The ITU citation was posted in message #29:
1.157  peak envelope power (of a radio transmitter): The average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope taken under normal operating conditions.

Notice it is based on one sinusoidal cycle as I stated.

A more accurate term for the often-used "RMS power" would be "RMS-derived power".  But that's a little harder to say.  What is being referenced is just "power", a calculation of work per unit time.

The auxiophools have their own loose definition of "RMS" power which we can safely ignore. My post was in response to message #14 that asserted RMS-derived power of a single tone SSB signal is 3dB less than PEP. A truly nonsense idea.

Taken literally, RMS power CAN exist but it is part of a statistical calculation of standard deviation of power over a period of time. [ed- This is the more obscure interpretation.]


Title: RE: 1500 pep output max
Post by: W5HRO on January 14, 2016, 12:37:58 PM
Taken literally, RMS power CAN exist but it is part of a statistical calculation of standard deviation of power over a period of time.

That's the only thing so far you have said that makes any sense. If you go back and read your post though that Carl responded to it's up in the stratosphere and makes no sense at all. The FCC and harmonic part is completely insane. That ITU citation is also badly worded. Average power and peak envelope power are NOT the same thing at all. They should remove the word "average" from the sentence.

Anyway, a lot of people including myself consider average or mean power just RMS power. Many of the old cheap power meters had those scales labeled as RMS. The problem is some just like to get really nit-picky on technical terms and definitions. It just like the majority of all hams pronounce GHz as Giga-Hertz when it’s is really pronounced Jiga-Hertz with a J. How many people do you ever hear pronounce GHz that way though? Almost none, right? That doesn't mean I'm going to come into a topic or QSO whenever I hear it pronounced Giga-Hertz and say “Hey, you are pronouncing GHz wrong”.

What’s important is that RMS power should never be confused with PEP. Average power and peak envelope power should never be considered as the same thing.

73’s


Title: RE: 1500 pep output max
Post by: KM1H on January 14, 2016, 02:26:55 PM
Wow! You probably believe the earth is flat also.

How about coming up with the FCC citation to support your "theory"?

Quote
The ITU citation was posted in message #29:
1.157  peak envelope power (of a radio transmitter): The average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope taken under normal operating conditions.


Youre not even intelligent enough to read, no wonder Ten Tec is down the tubes and the few I owned were pure junk....
https://www.qrz.com/lookup

From that same Post 29

Quote
Note that there are no references to "RMS Power" here, nor in any radio engineering texts.

Carl


Title: RE: 1500 pep output max
Post by: WB4JTR on January 14, 2016, 04:02:21 PM
Taken literally, RMS power CAN exist but it is part of a statistical calculation of standard deviation of power over a period of time.

That's the only thing so far you have said that makes any sense. If you go back and read your post though that Carl responded to it's up in the stratosphere and makes no sense at all. The FCC and harmonic part is completely insane. That ITU citation is also badly worded. Average power and peak envelope power are NOT the same thing at all. They should remove the word "average" from the sentence...

Check your math guys.  Power averaged over one sinewave cycle IS rms-derived power.  So the word "average" in the ITU text is correct.

And the FCC limit on harmonic content just ensures you are dealing with a sinewave.

Average power, in general, is not PEP.  But PEP is average power over the single RF cycle at the peak of the envelope.


Title: RE: 1500 pep output max
Post by: W5HRO on January 14, 2016, 05:14:43 PM
Check your math guys.  Power averaged over one sinewave cycle IS rms-derived power.  So the word "average" in the ITU text is correct.

Your statment read "RF power is always expressed as RMS because the waveform is always sinusoidal."

Unfortunately you have no idea what you are talking about, not in regards to PEP.

Average power, in general, is not PEP.  But PEP is average power over the single RF cycle at the peak of the envelope.

Average power is not PEP in general, it's not average power period.

P.S. The main problem is that you have been confusing carrier power with modulated envelope power.


Title: RE: 1500 pep output max
Post by: W5HRO on January 14, 2016, 06:19:01 PM
I did a quick search so to show you where your error is watch the Youtube video via the link below.

http://www.youtube.com/watch?v=pgzc4aU_HeY

Just after 7 minutes through the video around 7:23 he starts to draw the red average/mean (RF carrier) rectangle.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 14, 2016, 07:17:11 PM
Check your math guys.  Power averaged over one sinewave cycle IS rms-derived power.  So the word "average" in the ITU text is correct.

Your statment read "RF power is always expressed as RMS because the waveform is always sinusoidal."

Unfortunately you have no idea what you are talking about, not in regards to PEP.

Average power, in general, is not PEP.  But PEP is average power over the single RF cycle at the peak of the envelope.

Average power is not PEP in general, it's not average power period.

P.S. The main problem is that you have been confusing carrier power with modulated envelope power.

For PEP power, you can use the RMS calculation at the peak of the envelope because the waveform is ALWAYS just a sinewave.  (A sinewave contains no harmonics.)   That's why the ITU can use "average power over one cycle" to define PEP.  It's the same calculation the everyday rms/peak/average relations are based on for any sinewave.  And it's completely independent of envelope (modulation) shape.

Average power can not, in general, be PEP.  Average power in general depends on waveform shape.  But PEP is DEFINED as average power over a single cycle of a particular sinewave.  It is the LOCATION of this particular sinewave that is critical.  It must be located at the highest peak of the envelope.

We are discussing PEP of a SSB signal.  There is no carrier -- It is assumed to be completely suppressed.

PS:  I entered this thread to refute the assertion that the power in a single-tone SSB signal is 3dB below PEP.  To me, that's a crazy idea.  As far as the ITU's decision to base the definition of PEP on the average power in a particular sinewave, I completely understand their rationale.  How would you have defined it?



Title: RE: 1500 pep output max
Post by: W5HRO on January 14, 2016, 07:39:19 PM
because the waveform is ALWAYS just a sinewave.  (A sinewave contains no harmonics.)

No it is not and that's where you are wrong. You are right that a sinewave does not contain any 3rd order harmonics (be specific), but the PEP waveform is NOT always a sinewave.

I think most of us probably understand that you are referring to SSB and not AM and I'm only speaking for myself, but average power is mean power and is not PEP. Forget the fact that some people including myself tend to generalize avg/mean power as RMS power in discussions, but you have misinterpreted some basic facts.



Title: RE: 1500 pep output max
Post by: WB4JTR on January 14, 2016, 09:48:51 PM
because the waveform is ALWAYS just a sinewave.  (A sinewave contains no harmonics.)

No it is not and that's where you are wrong. You are right that a sinewave does not contain any 3rd order harmonics (be specific), but the PEP waveform is NOT always a sinewave.

I think most of us probably understand that you are referring to SSB and not AM and I'm only speaking for myself, but average power is mean power and is not PEP. Forget the fact that some people including myself tend to generalize avg/mean power as RMS power in discussions, but you have misinterpreted some basic facts.

A sinewave doesn't contain ANY harmonics.  Even harmonic distortion is also limited by the FCC.  If both odd and even orders weren't so limited, the single cycle on which PEP is based would be distorted, making the PEP calculation more difficult.

You keep repeating that average or mean power is not PEP.  That is true (as I have also repeated).  But PEP IS average (mean) power under the specific condition imposed by the ITU (and FCC).  By definition.  It is also RMS-derived power under the same condition.

I think the main problem here is failure to realize the time scale difference between the two concepts.  The average (mean) power used to define PEP is one RF cycle.  This is also the time scale used to establish the well-known peak/average/RMS sinewave relations.  The general audiophile concept of average power is based on a time scale of thousands of RF cycles.  And sometimes the RF waveform is ignored completely and averages are based on envelope or modulating audio alone.

In a way we're lucky PEP is based on the average (RMS) [ed-"RMS based"] power at the envelope peak.  Think what our 1500 watts would get us if it were based on the instantaneous peak power of that single cycle!


Title: RE: 1500 pep output max
Post by: KB8E on January 15, 2016, 02:40:25 AM
WB4JTR is correct. PEP is power overaged over one RF cycle at the peak of the modulation envelope. In other words, very short-term average power at the peak of the modulation. (Note: not instantaneous peak power as I stated in my first post in this topic. Sorry for that error and thanks to those who corrected me.) Think of the case of an unmodulated carrier; Since the modulation envelope is constant, any measurement of average power is correct. If the carrier is modulated, PEP represents the average power at the peak, as if the peak were to be sustained.

Sam


Title: RE: 1500 pep output max
Post by: W5HRO on January 15, 2016, 05:54:04 AM
because the waveform is ALWAYS just a sinewave.  (A sinewave contains no harmonics.)

No it is not and that's where you are wrong. You are right that a sinewave does not contain any 3rd order harmonics (be specific), but the PEP waveform is NOT always a sinewave.

I think most of us probably understand that you are referring to SSB and not AM and I'm only speaking for myself, but average power is mean power and is not PEP. Forget the fact that some people including myself tend to generalize avg/mean power as RMS power in discussions, but you have misinterpreted some basic facts.

A sinewave doesn't contain ANY harmonics.  Even harmonic distortion is also limited by the FCC.  If both odd and even orders weren't so limited, the single cycle on which PEP is based would be distorted, making the PEP calculation more difficult.

You keep repeating that average or mean power is not PEP.  That is true (as I have also repeated).  But PEP IS average (mean) power under the specific condition imposed by the ITU (and FCC).  By definition.  It is also RMS-derived power under the same condition.

I think the main problem here is failure to realize the time scale difference between the two concepts.  The average (mean) power used to define PEP is one RF cycle.  This is also the time scale used to establish the well-known peak/average/RMS sinewave relations.  The general audiophile concept of average power is based on a time scale of thousands of RF cycles.  And sometimes the RF waveform is ignored completely and averages are based on envelope or modulating audio alone.

In a way we're lucky PEP is based on the average (RMS) power at the envelope peak.  Think what our 1500 watts would get us if it were based on the instantaneous peak power of that single cycle!

A sinewave CAN contain even harmonics, but in RF applications it is not very critical. It is the sharp and/or flat edges of the instantaneous peaks in PEP that are the issue and like when someone overdrives their linear to where it flat-tops. Those will produce the 3rd order harmonics. Even order harmonics can be a good thing, but mainly in audio applications.

Forget what the FCC and the ITU say because it is insignificant. That's been the problem from the very beginning. In the REAL world PEP is NEVER a perfect one-cycle sinewave like you keep suggesting. RMS and PEP all do come from the same set of equations, but in the REAL world PEP with the human voice consists of instantaneous peaks which has nothing to do with average power unless you measure that average power, but it's still not PEP or what most people consider PEP to be.

You need to separate the in the clouds theoretical and the screwed-up FCC and ITU descriptions from the REAL world practical way things really are.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 15, 2016, 10:15:50 AM
WB4JTR is correct. PEP is power overaged over one RF cycle at the peak of the modulation envelope. In other words, very short-term average power at the peak of the modulation. (Note: not instantaneous peak power as I stated in my first post in this topic. Sorry for that error and thanks to those who corrected me.) Think of the case of an unmodulated carrier; Since the modulation envelope is constant, any measurement of average power is correct. If the carrier is modulated, PEP represents the average power at the peak, as if the peak were to be sustained.

Sam

Thank you Sam.  That is all I am trying to say.  All my statements are in the context of the post #14 which I endever to refute.  The original poster can speak for himself, but I can speculate where he went wrong:
If you ignore the RF waveform and base your calculations on the modulating single-tone sinewave, you could conclude that power derived from the RMS calculation is half the peak power.  But that is just flat wrong for a SSB signal.  The ITU (and FCC) got it right for calculating the difference between PEP and average (RMS-derived) power in this case.  The difference is exactly zero -- not 3dB.

Let's not go down the rabbit hole of long-term average power of voice-modulated envelopes of the sinewave RF waveform.  It's different for each voice and exact calculations require mathematics of which most hams (and more audiophiles) are unaware.

But the ITU got it right and expressed it correctly.  Deleting the word "average" from the text, as was suggested earlier, would break the analysis.

-Lee


Title: RE: 1500 pep output max
Post by: WB4JTR on January 15, 2016, 10:27:02 AM

A sinewave CAN contain even harmonics, but in RF applications it is not very critical. It is the sharp and/or flat edges of the instantaneous peaks in PEP that are the issue and like when someone overdrives their linear to where it flat-tops. Those will produce the 3rd order harmonics. Even order harmonics can be a good thing, but mainly in audio applications.

Forget what the FCC and the ITU say because it is insignificant. That's been the problem from the very beginning. In the REAL world PEP is NEVER a perfect one-cycle sinewave like you keep suggesting. RMS and PEP all do come from the same set of equations, but in the REAL world PEP with the human voice consists of instantaneous peaks which has nothing to do with average power unless you measure that average power, but it's still not PEP or what most people consider PEP to be.

You need to separate the in the clouds theoretical and the screwed-up FCC and ITU descriptions from the REAL world practical way things rea inlly are.

See message 77 above.

PS:  A single sinewave never contains even or odd harmonics.  It takes a summation of sinewaves to represent any harmonic distortion.  And even harmonics of the RF signal are harder to filter than odds -- the first one is closer to the fundamental.  I think you have confused harmonics with IMD.


Title: RE: 1500 pep output max
Post by: W5HRO on January 15, 2016, 11:04:24 AM
A perfect symmetrical waveform will not produce any harmonics even or odd, but a perfect symmetrical waveform does NOT exist in the real world and that's what you keep missing ::)

In the REAL world with 80% to 90% hams running tube linears biased in AB2 the lower operating point of AB2 introduces harmonic distortion to the modulated waveform anyway. However, if the distortion is not distortion from flat-topping or from other anomalies that create sharp edges then the distortion will generally be of even-order which can be a good thing. What it will do is increase the modulated bandwidth and audio fidelity. However, for every repetition of the fundamental frequency there are two repetitions of the 2nd harmonic along with three repetitions of the 3rd harmonic, but the level of those 3rd harmonic repetitions are usually so low they are insignificant.

Now, if someone over-drives their tube AB2 linear into flat-topping and/or produces sharp edges like many hams operating on SSB do today then It will produce lots of trash that will show up on a spectrum analyzer. That or if they are using and over-driving solid-state audio equipment and/or solid-state linears. It will always be 3rd order and much worse. One of the benefits of using vacuum tube equipment is that you can generate the even-order harmonics and obtain better fidelity doing so. That is one area where some Audiophiles actually no more than some Radiophools.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 15, 2016, 11:32:08 AM
A perfect symmetrical waveform will not produce any harmonics even or odd, but a perfect symmetrical waveform does NOT exist in the real world and that's what you keep missing ::)

In the REAL world with 80% to 90% hams running tube linears biased in AB2 the lower operating point of AB2 introduces harmonic distortion to the modulated waveform anyway. However, if the distortion is not distortion from flat-topping or from other anomalies that create sharp edges then the distortion will generally be of even-order which can be a good thing. What it will do is increase the modulated bandwidth and audio fidelity. However, for every repetition of the fundamental frequency there are two repetitions of the 2nd harmonic along with three repetitions of the 3rd harmonic, but the level of those 3rd harmonic repetitions are usually so low they are insignificant.

Now, if someone over-drives their tube AB2 linear into flat-topping and/or produces sharp edges like many hams operating on SSB do today then It will produce lots of trash that will show up on a spectrum analyzer. That or if they are using and over-driving solid-state audio equipment and/or solid-state linears. It will always be 3rd order and much worse. One of the benefits of using vacuum tube equipment is that you can generate the even-order harmonics and obtain better fidelity doing so. That is one area where some Audiophiles actually no more than some Radiophools.


As I suspected, you have presented a general discussion of IMD.  It's mostly true, but out of context in the present discussion.

Please see message #77 above.


Title: RE: 1500 pep output max
Post by: W5HRO on January 15, 2016, 01:08:21 PM
As I suspected, you have presented a general discussion of IMD.  It's mostly true, but out of context in the present discussion.

It has nothing to do with that and I was right on point. You have been referring to a perfect symmetrical sinewave from the FCC and ITU specs which does NOT exist with either the human voice (voice communications) or music.

If a perfect symmetrical sinewave did exist the amplifier bias class (or operating point) of what ham operators actually use would distort it one way or another anyway. Only class A amplifiers can come close to producing an exact replica of a perfect symmetrical sinewave if a perfect symmetrical sinewave was inputted.

The main point is that the human voice does not produce a symmetrical sinewave so quoting what is written in the FCC and ITU specs does not apply because they are not real world representations of what actually happens.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 15, 2016, 03:15:32 PM
As I suspected, you have presented a general discussion of IMD.  It's mostly true, but out of context in the present discussion.

It has nothing to do with that and I was right on point. You have been referring to a perfect symmetrical sinewave from the FCC and ITU specs which does NOT exist with either the human voice (voice communications) or music.

If a perfect symmetrical sinewave did exist the amplifier bias class (or operating point) of what ham operators actually use would distort it one way or another anyway. Only class A amplifiers can come close to producing an exact replica of a perfect symmetrical sinewave if a perfect symmetrical sinewave was inputted.

The main point is that the human voice does not produce a symmetrical sinewave so quoting what is written in the FCC and ITU specs does not apply because they are not real world representations of what actually happens.

There is absolutely no requirement for a perfect RF sinewave.  It only has to be close enough to satisfy the FCC regs.  That is plenty close enough to allow use of the sinewave relations for peak/RMS/average.  The calculations will be far more accurate than any 'scope, spectrum analyzer, or meter (even after corrections for average-responding movements).

And even if you suspect your waveform doesn't meet FCC regs, here's the surprise:
The ITU regulators were pretty smart.  Even if the RF cycle of interest is not a good sinewave, the calculation for PEP still works!  This is a result of the definition being based on average power of a single cycle (the basic concept of RMS).

So the ITU definition is robust.  If you suspect your RF cycle is not clean enough, just break out the calculus and follow the definition explicitly.  Your result will still be true PEP -- just realize all of the power won't be on the operating frequency.  Some of the PEP will be out of the band at the harmonics of your frequency (in violation of the regs).

Don't confuse the single cycle used for the PEP definition with the audio modulation waveform and IMD effects.  Also realize PEP is defined at the output to the antenna -- after harmonic filtering.


Title: RE: 1500 pep output max
Post by: W5HRO on January 15, 2016, 06:56:11 PM
There is absolutely no requirement for a perfect RF sinewave.  It only has to be close enough to satisfy the FCC regs.  That is plenty close enough to allow use of the sinewave relations for peak/RMS/average.  The calculations will be far more accurate than any 'scope, spectrum analyzer, or meter (even after corrections for average-responding movements).

I never said there was, you did.

Quote
And even if you suspect your waveform doesn't meet FCC regs, here's the surprise:
The ITU regulators were pretty smart.  Even if the RF cycle of interest is not a good sinewave, the calculation for PEP still works!  This is a result of the definition being based on average power of a single cycle (the basic concept of RMS).

It's pointless trying to meet that so called FCC requirement because it is not valid in the real world.

Quote
So the ITU definition is robust.  If you suspect your RF cycle is not clean enough, just break out the calculus and follow the definition explicitly.  Your result will still be true PEP -- just realize all of the power won't be on the operating frequency.  Some of the PEP will be out of the band at the harmonics of your frequency (in violation of the regs).

Only a meter that can measure true Average power will be accurate. Another member already posted one previously. PEP is a nonsense measurment and it's pointless trying to meet it.

Quote
Don't confuse the single cycle used for the PEP definition with the audio modulation waveform and IMD effects.  Also realize PEP is defined at the output to the antenna -- after harmonic filtering.

I'm not confusing anything. The only person who has been confused is you.


Title: RE: 1500 pep output max
Post by: W9IQ on January 15, 2016, 08:24:09 PM
You may wish to debate your preferred method of power measurement but in the end, PEP limits are a regulatory requirement in the US. Until you convince the FCC to change the regulations, your "better" way doesn't convey any regulatory significance - at best it could be described as an additional metric.

The good thing is that PEP is well defined, it is relatively easy to measure, it works for all modulation modes, and it spans all amplifier classes. It is also independent of voice characteristics, assuming all voices are capable of the same modulation peak (ideally 100% modulation) at some time in their speech pattern (particularly applicable to SSB).

You can of course use various processing techniques to improve your average output power and still meet the PEP limits set forth in the regulations. Coincidentally, there is a nice article by W9GR on CESS for SSB in the February 2016 issue of QST to this very point. Dave sites a ~3.6 dB improvement in average power for the same PEP power while eliminating the need for ALC. The takeaway for this thread is that the technique can still meet the PEP regulatory requirement while improving average power (and most likely the receiver's S meter reading).

- Glenn W9IQ





Title: RE: 1500 pep output max
Post by: WB4JTR on January 15, 2016, 08:39:38 PM
There is absolutely no requirement for a perfect RF sinewave.  It only has to be close enough to satisfy the FCC regs.  That is plenty close enough to allow use of the sinewave relations for peak/RMS/average.  The calculations will be far more accurate than any 'scope, spectrum analyzer, or meter (even after corrections for average-responding movements).

I never said there was, you did.

Quote
And even if you suspect your waveform doesn't meet FCC regs, here's the surprise:
The ITU regulators were pretty smart.  Even if the RF cycle of interest is not a good sinewave, the calculation for PEP still works!  This is a result of the definition being based on average power of a single cycle (the basic concept of RMS).

It's pointless trying to meet that so called FCC requirement because it is not valid in the real world.

Quote
So the ITU definition is robust.  If you suspect your RF cycle is not clean enough, just break out the calculus and follow the definition explicitly.  Your result will still be true PEP -- just realize all of the power won't be on the operating frequency.  Some of the PEP will be out of the band at the harmonics of your frequency (in violation of the regs).

Only a meter that can measure true Average power will be accurate. Another member already posted one previously. PEP is a nonsense measurment and it's pointless trying to meet it.

Quote
Don't confuse the single cycle used for the PEP definition with the
 audio modulation waveform and IMD effects.  Also realize PEP is defined at the output to the antenna -- after harmonic filtering.

I'm not confusing anything. The only person who has been confused is you.

If I ever said a perfect RF sinewave is required I was wrong.  That requirement would mean the FCC regs call for infinite attenuation in the harmonic filtering.  Truly impractical.  The harmonic content is only LIMITED by regulation.  And that limit is low enough that the sinewave RMS/average/peak relations can be used in practice.  But as I demonstrated above, if you are so concerned about the purity of the sinewave, don't worry -- the ITU definition still describes a perfectly accurate PEP.  You don't really have to use the sinewave relations to get there -- it's just a little more difficult calculation.

Meeting the ITU/FCC maximum PEP requirement is not pointless.  It is done regularly and successfully all over the world.  Just be aware of the accuracy limit of your measurement system and stay that far below the limit -- you'll be safe.

PEP measurement is not nonsense.  CW power output can be measured accurately enough and used as a reference on any old 'scope to set a reference for accurate PEP 2-tone, multi-tone, or voice/music measurements.  Even band-limited white noise can be used to check PEP, if desired.

I assumed your presentation on audio and envelope distortion caused by non-linearity and IMD effects to be due to confusion of the modulation waveform with the RF waveform cycle on which PEP is defined.  My bad...I guess it was just a non sequitur.


Title: RE: 1500 pep output max
Post by: W5HRO on January 16, 2016, 07:59:32 AM
You can just keep going on and on here and you have already contradicted yourself once or twice but you are still wrong nevertheless.

PEP is in fact a real measurement if you inject a perfect symmetrical waveform using a generator, but it's shape will still be slightly altered (distorted) after going through the audio and RF amplifier circuits ham operators use so in the end it will not be an exact replica of what was inputted, but it will be close enough for a so-so-measurement. It will never be 100% textbook exact though.

What blows PEP out of the water and its use as a measurement in the real world is the fact that the human voice produces an asymmetrical waveform that’s shape and level constantly changes as a person talks so the only real way to measure it is to take an average measurement of it over a time period and not just using one single cycle. A good and true avg/mean power reading meter will work the best.

You yourself can kept debating otherwise, but in the end you will still be wrong no matter what you say.

Have a good one...

73's


Title: RE: 1500 pep output max
Post by: WB4JTR on January 16, 2016, 09:31:52 AM
You can just keep going on and on here and you have already contradicted yourself once or twice but you are still wrong nevertheless.

PEP is in fact a real measurement if you inject a perfect symmetrical waveform using a generator, but it's shape will still be slightly altered (distorted) after going through the audio and RF amplifier circuits ham operators use so in the end it will not be an exact replica of what was inputted, but it will be close enough for a so-so-measurement. It will never be 100% textbook exact though.

What blows PEP out of the water and its use as a measurement in the real world is the fact that the human voice produces an asymmetrical waveform that’s shape and level constantly changes as a person talks so the only real way to measure it is to take an average measurement of it over a time period and not just using one single cycle. A good and true avg/mean power reading meter will work the best.

You yourself can kept debating otherwise, but in the end you will still be wrong no matter what you say.

Have a good one...

73's

PEP has no "shape".  It is a number: "watts"' easily measured and independent of audio or envelope shape or distortion.

You should take your discussions of audio harmonic and IMD distortion to another thread. They are non sequiturs here.  There is certainly some truth in them but they can only relate to "strawmen" here.

Your proposed procedure of "The only real way to measure it is to take an average measurement of it over a time period and not just using one single cycle." Will not produce anything close to PEP.

The purpose of this thread is to explain why single-tone SSB is not 3dB below PEP.  I think that has been accomplished.

Move on.



Title: RE: 1500 pep output max
Post by: KM1H on January 16, 2016, 11:49:45 AM
PEP is power overaged over one RF cycle at the peak of the modulation envelope. In other words, very short-term average power at the peak of the modulation.

Sam

Of course that definition is correct as it is clearly spelled out in the FCC rules for decades now to anyone who takes the time to look it up.

However this cant be defined as RMS power since it simply has not been defined in engineering textbooks, journals, FCC, nor the IEEE.
IOW it is purely an invented term with no basis in fact and simply a carry over from Sears and other audio amp manufacturers who jacked up the power using a marketing managers formula squeezed out on the throne one morning. They carried it over to horsepower also.

Im still waiting for a legitimate citation from a USA source (not an individual) that claims otherwise. I say USA since this is about a FCC rule. If Im wrong an apology will be forthcoming. Meanwhile please stop all the meaningless verbal dancing, damage control or whatever else someone wishes to call it.

Carl


Title: RE: 1500 pep output max
Post by: K4KYV on January 16, 2016, 04:29:58 PM
...it is purely an invented term with no basis in fact and simply a carry over from Sears and other audio amp manufacturers who jacked up the power using a marketing managers formula squeezed out on the throne one morning...

Like the p.e.p. amateur radio power rule.

Quote
I say USA since this is about a FCC rule.

As far as I know the USA was the first country to adopt p.e.p. as the amateur radio power standard, then other countries followed suit and adopted into their rules. Totally irrelevant to the fundamental purpose of a power limit in the rules of the amateur or any other radio service.


Title: RE: 1500 pep output max
Post by: W6RZ on January 16, 2016, 05:36:13 PM
Easily simulated and hopefully a graphical representation will be helpful. Here's an SSB waveform at an RF frequency of 500 kHz. The first graph is for 1 second of time. It's showing syllables, and the peak at about 0.4 seconds is the first syllable of the word "dedicated".

(http://www.w6rz.net/ssbpep1.png)

Next graph is zoomed in 10x. 100 milliseconds of waveform.

(http://www.w6rz.net/ssbpep2.png)

Zoom in another 10x. 10 milliseconds of waveform.

(http://www.w6rz.net/ssbpep3.png)

Zoom in another 10X. 1 millisecond of waveform.

(http://www.w6rz.net/ssbpep4.png)

Zoom in another 5X. 200 microseconds of waveform. At this scale, we're starting to see individual RF cycles, but can still see part of the envelope.

(http://www.w6rz.net/ssbpep5.png)

Zoom in another 4X. 50 microseconds of waveform or 25 sine wave cycles at 500 kHz. Same as a CW waveform. The power of 1 cycle (used in the FCC and ITU definition of PEP) is the same as the power over 25 cycles.

(http://www.w6rz.net/ssbpep6.png)

The maximum PEP power of the original 1 second waveform is then calculated by taking the maximum RMS value of the voltage waveform, squaring it and dividing by 50 ohms (what WB4JTR is calling "RMS derived power"). That is, ((0.5 * 0.7071) * (0.5 * 0.7071)) / 50 = 2.5 milliwatts.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 16, 2016, 05:40:27 PM
PEP is power overaged over one RF cycle at the peak of the modulation envelope. In other words, very short-term average power at the peak of the modulation.

Sam

Of course that definition is correct as it is clearly spelled out in the FCC rules for decades now to anyone who takes the time to look it up.

However this cant be defined as RMS power since it simply has not been defined in engineering textbooks, journals, FCC, nor the IEEE....

Carl

I thought we decided not to use the term "RMS power" because it is ambiguous.  "RMS derived" power is a good substitute.

The power in the ITU/FCC definition IS equivalent to RMS derived power.  In fact, the definition of RMS uses the same concept: "Average the squared function (voltage or current in the case of electrical functions) value over the complete cycle, then take the square root."  To derive power from these two numbers (RMS voltage and current) multiply them together.  The result of this procedure is simply the average instantaneous power over one cycle.  Sound familiar?  It's exactly equivalent to the ITU/FCC value for PEP.

You don't need an IEEE reference to this concept.  You can look it up in any basic engineering text.

-Lee

PS:  The W6RZ demo above is correct.  Thanks, OM. :)


Title: RE: 1500 pep output max
Post by: KM1H on January 16, 2016, 06:53:17 PM
Quote
I thought we decided not to use the term "RMS power" because it is ambiguous.  "RMS derived" power is a good substitute.

I dont know who "we" is or when you gave up on trying to force RMS Power on everybody as trying to read all the back and forth gave me a headache.

Quote
The power in the ITU/FCC definition IS equivalent to RMS derived power.  In fact, the definition of RMS uses the same concept: "Average the squared function (voltage or current in the case of electrical functions) value over the complete cycle, then take the square root."  To derive power from these two numbers (RMS voltage and current) multiply them together.  The result of this procedure is simply the average instantaneous power over one cycle.  Sound familiar?  It's exactly equivalent to the ITU/FCC value for PEP.

PEP is an accepted standard, RMS Power or Derived Power is not. It is simply less than a handful on an obscure hobby forum who want to confuse the issue by applying it that way.

Quote
You don't need an IEEE reference to this concept.  You can look it up in any basic engineering text.

Engineering definitions and naming are referred to a standards committee known as the IEEE-SA or arent you aware of that?  I cant find either of your versions even mentioned.

I think this thread should be terminated before it gets out of hand with alternate versions of reality and wasted bandwidth graphs that simply say what was already in the extremely simple and short explanation in the FCC rules for decades which any entry level AC power tech should be able to understand without having to get into unecessary math to make the conversion. I wonder how many of the dumbed down Extra Class era are able to handle it without grabbing for reference material?

Carl


Title: RE: 1500 pep output max
Post by: WB4JTR on January 16, 2016, 08:16:44 PM
Quote
I thought we decided not to use the term "RMS power" because it is ambiguous.  "RMS derived" power is a good substitute.

I dont know who "we" is or when you gave up on trying to force RMS Power on everybody as trying to read all the back and forth gave me a headache.

Quote
The power in the ITU/FCC definition IS equivalent to RMS derived power.  In fact, the definition of RMS uses the same concept: "Average the squared function (voltage or current in the case of electrical functions) value over the complete cycle, then take the square root."  To derive power from these two numbers (RMS voltage and current) multiply them together.  The result of this procedure is simply the average instantaneous power over one cycle.  Sound familiar?  It's exactly equivalent to the ITU/FCC value for PEP.

PEP is an accepted standard, RMS Power or Derived Power is not. It is simply less than a handful on an obscure hobby forum who want to confuse the issue by applying it that way.

Quote
You don't need an IEEE reference to this concept.  You can look it up in any basic engineering text.

Engineering definitions and naming are referred to a standards committee known as the IEEE-SA or arent you aware of that?  I cant find either of your versions even mentioned.

I think this thread should be terminated before it gets out of hand with alternate versions of reality and wasted bandwidth graphs that simply say what was already in the extremely simple and short explanation in the FCC rules for decades which any entry level AC power tech should be able to understand without having to get into unecessary math to make the conversion. I wonder how many of the dumbed down Extra Class era are able to handle it without grabbing for reference material?

Carl

Interesting.  If someone asked you to explain what PEP is and how to compute it, how would YOU derive the power in that cycle as mandated by the ITU/FCC?  Especially if that cycle is not a perfect sinewave (as someone keeps insisting).  And what would you call the result of your derivation to distinguish it from the other derivations of power (instaneous peak, average, etc)?  I like the description "RMS-derived power", but you are free to coin your own descriptive term.  Or go ahead and use "RMS power" -- but be prepared to explain yourself if somebody takes it the wrong way.

I'm sure the reason we don't see the term "RMS power" in the books is because of it's ambiguity (power from RMS data or the RMS value of a set of power data values?).  Unfortunately, it's absence from the literature has not prevented it's common use to refer to power from RMS data.


Title: RE: 1500 pep output max
Post by: W1BR on January 16, 2016, 08:40:37 PM
It would seem to me the purity of the RF output relating to being a pure sine wave is entirely dependent on the tank circuit Q.  The tube basically is a switch. The tank Q provides the flywheel effect over the full AC cycle.

Pete


Title: RE: 1500 pep output max
Post by: WB4JTR on January 16, 2016, 08:50:34 PM
It would seem to me the purity of the RF output relating to being a pure sine wave is entirely dependent on the tank circuit Q.  The tube basically is a switch. The tank Q provides the flywheel effect over the full AC cycle.

Pete

Bingo!


Title: RE: 1500 pep output max
Post by: K6BRN on January 17, 2016, 12:34:52 AM
Very strange cult for/against "RMS power" in this thread.  Its like being for/against ... water.  Makes no sense arguing that it does not exist, whether it is a "standard" in the amateur community or not, the terminology is in use in industry and is usually equated with average power.

RMS RF power "measurement" is very common and lots of RF parts exist specifically to do this.  For example, the Linear Technologies LT5587, the Analog Devices ADL5502, the Maxim MAXX2203, and the Hittite HMC1030LP5E all are intended to measure "RF RMS power" - usually as an inline estimator of "Average Power" calculated from measured RMS voltage values.

Regarding books discussing this explicitly, see "Engineering Circuit Analysis" by Hayt and Kemmerly, which is a first year EE text used by almost every accredited program in the USA.  Chapter 11, in my ancient copy.  Plenty of detail on the topic, too.

Not sure where the "Determined Denial" camp is coming from.  Splitting hairs, perhaps, or terminology evangelists?  Makes as much sense as trying to resolve the difference between "flammable" and "inflammable" when there is none, even though there should be.



Title: RE: 1500 pep output max
Post by: SM0AOM on January 17, 2016, 01:11:08 AM

As far as I know the USA was the first country to adopt p.e.p. as the amateur radio power standard, then other countries followed suit and adopted into their rules. Totally irrelevant to the fundamental purpose of a power limit in the rules of the amateur or any other radio service.

Actually the use of PEP as a metric for amateur radio power limitations was first used in the British GPO rules in the mid/late 50's when SSB was introduced. The GPO limited amateur radio to a maximum of 150 W DC input in their post-war rules, and was not willing to "budge" in this respect.

Proponents of SSB felt that SSB was disadvantaged with respect to AM if this power rule would be used in the future,
so a compromise was worked out.

It resulted in an SSB power limit that was expressed as the PEP output resulting from a 100% modulated carrier from a typical AM transmitter with 150W input. This worked out to 400 W PEP, and stays to this day.

Later changes permitted also other emissions than SSB to use the PEP rating, so CW ultimately got a 6 dB advantage compared to the old 150 W DC input rule.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 05:56:49 AM
Very strange cult for/against "RMS power" in this thread.  Its like being for/against ... water.  Makes no sense arguing that it does not exist, whether it is a "standard" in the amateur community or not, the terminology is in use in industry and is usually equated with average power.

RMS RF power "measurement" is very common and lots of RF parts exist specifically to do this.  For example, the Linear Technologies LT5587, the Analog Devices ADL5502, the Maxim MAXX2203, and the Hittite HMC1030LP5E all are intended to measure "RF RMS power" - usually as an inline estimator of "Average Power" calculated from measured RMS voltage values.

Regarding books discussing this explicitly, see "Engineering Circuit Analysis" by Hayt and Kemmerly, which is a first year EE text used by almost every accredited program in the USA.  Chapter 11, in my ancient copy.  Plenty of detail on the topic, too.

Not sure where the "Determined Denial" camp is coming from.  Splitting hairs, perhaps, or terminology evangelists?  Makes as much sense as trying to resolve the difference between "flammable" and "inflammable" when there is none, even though there should be.



Thank you BRN.  Well said.

-Lee


Title: RE: 1500 pep output max
Post by: W5HRO on January 17, 2016, 07:26:58 AM
RMS RF power "measurement" is very common and lots of RF parts exist specifically to do this.  For example, the Linear Technologies LT5587, the Analog Devices ADL5502, the Maxim MAXX2203, and the Hittite HMC1030LP5E all are intended to measure "RF RMS power" - usually as an inline estimator of "Average Power" calculated from measured RMS voltage values.

I work for LTC and yes, we do have a device for measuring true RMS power. RMS power does in fact exist like many don't want to believe and I gave up trying to explain that to the Radiophools on these hams boards, but it's a very complicated measurement method which can still  be done nevertheless. You just won't find RF power meters out there in the mainstream that will do it. Average reading power meters work good enough for the amateur radio and broadcast communities.

As far as the comment that PEP has no shape, that person just blew his entire argument out of the water. The PEP modulation envelope is determined by the audio waveform like the human voice used to modulate the RF or RF supply which creates that envelope. It makes you wonder how that guy ever became a radio engineer.


Title: RE: 1500 pep output max
Post by: W5HRO on January 17, 2016, 07:53:19 AM
It would seem to me the purity of the RF output relating to being a pure sine wave is entirely dependent on the tank circuit Q.  The tube basically is a switch. The tank Q provides the flywheel effect over the full AC cycle.

Absolutely, that too. I was focused mainly on trying to explain to the guy that most amplifiers hams use operate at a bias point (class) where the shape of PEP envelope will always be slightly distorted anyway and will always contain harmonics so it wont matter. A tube amp if not overdriven will almost always contain some level of even-order harmonics and solid-sate amps odd-order harmonics. The tubes and transistors will do that all by themselves so they are not just a switch. That is true for both audio amps and RF amps.

Now, with RF tuned circuits those harmonics will be attenuated some, it just depends on how much and those circuits can also distort the shape of the modulated PEP envelope further, but that’s another topic.




Title: RE: 1500 pep output max
Post by: WB4SPT on January 17, 2016, 08:02:57 AM
Since we can't collectively converge on a solution for power, perhaps we try to talk voltage limits instead.  I'll submit we limit our stations to 386 Volts peak into a 50 Ohm load.   ::)


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 08:11:10 AM
RMS RF power "measurement" is very common and lots of RF parts exist specifically to do this.  For example, the Linear Technologies LT5587, the Analog Devices ADL5502, the Maxim MAXX2203, and the Hittite HMC1030LP5E all are intended to measure "RF RMS power" - usually as an inline estimator of "Average Power" calculated from measured RMS voltage values.

I work for LTC and yes, we do have a device for measuring true RMS power. RMS power does in fact exist like many don't want to believe and I gave up trying to explain that to the Radiophools on these hams boards, but it's a very complicated measurement method which can still  be done nevertheless. You just won't find RF power meters out there in the mainstream that will do it. Average reading power meters work good enough for the amateur radio and broadcast communities.

As far as the comment that PEP has no shape, that person just blew his entire argument out of the water. The PEP modulation envelope is determined by the audio waveform like the human voice used to modulate the RF or RF supply which creates that envelope. It makes you wonder how that guy ever became a radio engineer.

(sigh)... Check your definition of scalar quantity.  That's what PEP is.  No shape allowed.

To W6RZ:  Thanks again for the simulation.  It clearly demonstrates the difference in time scale of the PEP definition and any property of the audio or envelope wave forms.  I mentioned this early in the "discussion".  That's what makes PEP independent of envelope waveform, and why the CW PEP of those 25 cycles is the same as the voice waveform as you demonstrated.

These concepts are indeed what "any entry level AC power tech should learn".



Title: RE: 1500 pep output max
Post by: W5HRO on January 17, 2016, 09:03:53 AM
(sigh)... Check your definition of scalar quantity.  That's what PEP is.  No shape allowed.

Quit quoting those FCC and ITU specs. That's where your confusion is coming from; they are not valid with voice communications or music. The descriptions only work for CW and any other mode that only involves a transmitted carrier that is not modulated by intelligence unless it's a single tone at constant level and frequency. The descriptions are not valid for SSB or AM.

These concepts are indeed what "any entry level AC power tech should learn".

The problem with many amateur radio people or people with strictly RF backgrounds is that they usually have a very narrow focus and area of expertise. So narrow that they tend to call anything outside of that narrow focus nonsense and it's usually just due to their own ignorance. When they don't understand something they resort to quoting something in a published document instead, even it has limitations or is some cases is not even valid to the discussion.


Title: RE: 1500 pep output max
Post by: K4KYV on January 17, 2016, 09:50:40 AM
RMS power does in fact exist like many don't want to believe and I gave up trying to explain that to the Radiophools on these hams boards, but it's a very complicated measurement method which can still  be done nevertheless. You just won't find RF power meters out there in the mainstream that will do it. Average reading power meters work good enough for the amateur radio and broadcast communities.

Please explain exactly what is the difference between this alleged "RMS power", and average (aka mean) power? Can you cite a reputable engineering text that gives a definition of "RMS power"?

Yes, this is more than mere semantics. In the field of science and engineering, language must be precise.  There is no place for sloppy definitions, mythology or pseudo-science.

Regarding the amateur power limit, this thread perfectly exemplifies the FCC's folly in a one-size-fits-all p.e.p. power limit.  Few of to-day's licensed amateurs understand or could correctly explain exactly what p.e.p. is, let alone accurately measure it, particularly when feeding a typical real-world amateur radio antenna.  The FCC admitted as much when they adopted the rule.  Under the old (DC input) power rule, amateur transmitters running at 90% or more of the legal limit were required to possess the necessary instruments to accurately measure transmitter power. Such a requirement was deleted under the new standard. In the proposal and R&O (to paraphrase) the FCC stated that amateurs wouldn't be required to actually measure transmitter power, only to comply with the limit, and in event of a station inspection the FCC agent would take care of the measuring.  Then they went on to say that amateurs have "means other than accurate measurement" to determine transmitter power, whatever that is supposed to mean.

Some make a big hullabaloo over the limit on p.e.p. and whether or not an errant voice peak might happen to "peek" a little above the magic number, yet another provision of the power limit rule is routinely ignored without second thought, the one at the very top of the list:

§97.313   Transmitter power standards.
(a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 10:18:16 AM
Since we can't collectively converge on a solution for power, perhaps we try to talk voltage limits instead.  I'll submit we limit our stations to 386 Volts peak into a 50 Ohm load.   ::)

I like that, but we shouldn't restrict everyone to a 50 ohm load.  PEP is just as easy to measure and works for any load.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 10:30:09 AM
(sigh)... Check your definition of scalar quantity.  That's what PEP is.  No shape allowed.

Quit quoting those FCC and ITU specs. That's where your confusion is coming from; they are not valid with voice communications or music. The descriptions only work for CW and any other mode that only involves a transmitted carrier that is not modulated by intelligence unless it's a single tone at constant level and frequency. The descriptions are not valid for SSB or AM...

If PEP only applied to unmodulated signals, there would be no need for it at all!  The W6RZ demo showed that it is accurate for voice modulated SSB.

The scalar property of watts is not from the ITU.  It's from your basic physics.  Want to talk about metrics of time varying watts?  Now you are into the second logical interpretation of "RMS power" I mentioned above.  Don't take us down that rabbit hole of statistics and standard deviations.  We could all end up riding the bandersnatch.




Title: RE: 1500 pep output max
Post by: W5HRO on January 17, 2016, 11:10:24 AM
Don,

I'm not going to site any publication or get into a debate with you regarding any of this. You had your mind made up on the subject long ago and you can take that to insinuate anything you want it to. I simply do not care.

The only thing I will say is that not all Audiophilies are Audiophools and some of the recent discussions regarding RMS and its use as a power measurement in audio applications for example is not B.S. Sometimes it is actually valid and it can also be used to more accurately measure modulated RF envelope power. It just requires a much more complicated sampling and conversion method unlike what you find in most all  powers meters on the market.


Title: RE: 1500 pep output max
Post by: W5HRO on January 17, 2016, 11:19:05 AM
If PEP only applied to unmodulated signals, there would be no need for it at all!

Because you have been talking about a perfect sinwave which you will never get on SSB or AM with a human voice. However, you will get one close to that with an unmodulated carrier. CW may not consist of a modulated envelope, but it’s the only way you will get a sinewave close to that where a PEP measurement would be useful or valid. It would be nothing more than just a peak-to-peak measurement unless you inject a tone and at a consistent level and audio frequency.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 11:41:12 AM
If PEP only applied to unmodulated signals, there would be no need for it at all!

Because you have been talking about a perfect sinwave which you will never get on SSB or AM with a human voice. However, you will get one close to that with an unmodulated carrier. CW may not consist of a modulated envelope, but it’s the only way you will get a sinewave close to that where a PEP measurement would be useful or valid. It would be nothing more than just a peak-to-peak measurement.

I don't know... That sinewave looks pretty close to me.  Check the demo again.  That's with voice modulation.  If you're within FCC specs for harmonic output, the RF sinewave will be plenty pure enough for an accurate PEP measurement with a 'scope after calibration with a reference CW signal and any wattmeter of your choice.  Just be sure you know the accuracy of your meter with a CW signal and set your reference that much lower than the reg.  No need for fancy RMS calculating meters or bolometers.


Title: RE: 1500 pep output max
Post by: W5HRO on January 17, 2016, 11:59:05 AM
I don't know... That sinewave looks pretty close to me.  Check the demo again.  That's with voice modulation.  If you're within FCC specs for harmonic output, the RF sinewave will be plenty pure enough for an accurate PEP measurement with a 'scope after calibration with a reference CW signal and any wattmeter of your choice.  Just be sure you know the accuracy of your meter with a CW signal and set your reference that much lower than the reg.  No need for fancy RMS calculating meters or bolometers.

I generally just check my carrier level with a Bird 43 then look at it on the scope and then use that peak-to-peak carrier reference for a reference. Then using simple math when I modulate I know where the limits on the scope are for the envelopes peaks both above and below that carrier reference. Usually my carrier far exceeds the 375W limit myth and that is in fact nothing but a myth. That's for AM though, after I determine where those above and below peaks are I can use that for SSB when the carrier is nulled out.

If ever buy one of those bird average reading meters like Don posted I will just use it instead and not even worry about it and just use the scope every once and a while.


Title: RE: 1500 pep output max
Post by: K6BRN on January 17, 2016, 12:00:23 PM
Don:

Regarding books covering RMS power, see my previous post citing the standard text for first year EEs in the USA, Hyatt and Kemmerly.  You might benefit from reading this basic Engineering text as it explains in detail how any waveform can be constructed from series of sine/cosine waves and how RMS values are used to calculate power.  Chapter 11 is where to start, if you have the engineering/mathematical background.

SSB, AM, QPSK...  RMS works for all of them.

Regarding precise terminology, mean power and average power are two very different metrics.  Please look up the definitions of "Mean" and "Average".  They are not the same at all.  "Let those who are without....."


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 01:19:30 PM
I generally just check my carrier level with a Bird 43 then look at it on the scope and then use that peak-to-peak carrier reference for a reference. Then using simple math when I modulate I know where the limits on the scope are for the envelopes peaks both above and below that carrier reference. Usually my carrier far exceeds the 375W limit myth and that is in fact nothing but a myth. That's for AM though, after I determine where those above and below peaks are I can use that for SSB when the carrier is nulled out.

If ever buy one of those bird average reading meters like Don posted I will just use it instead and not even worry about it and just use the scope every once and a while.

Sounds like good enough practice to me.

-Lee


Title: RE: 1500 pep output max
Post by: KM1H on January 17, 2016, 03:48:59 PM
Quote
Interesting.  If someone asked you to explain what PEP is and how to compute it, how would YOU derive the power in that cycle as mandated by the ITU/FCC?  Especially if that cycle is not a perfect sinewave (as someone keeps insisting).  And what would you call the result of your derivation to distinguish it from the other derivations of power (instaneous peak, average, etc)?  I like the description "RMS-derived power", but you are free to coin your own descriptive term.  Or go ahead and use "RMS power" -- but be prepared to explain yourself if somebody takes it the wrong way.

I'm sure the reason we don't see the term "RMS power" in the books is because of it's ambiguity (power from RMS data or the RMS value of a set of power data values?).  Unfortunately, it's absence from the literature has not prevented it's common use to refer to power from RMS data.


I would first tell them to ignore everything you say as it is doing no good by deliberately splitting into warring factions which I suspect is your primary goal.

I would then refer them to an excellent presentation by an accredited expert on the subject and this paper he wrote.
http://www.dudleylab.com/Appnote-4-Power-tests1.pdf.

That should satisfy all but an argumentative minority who should then go to the PreciseRF Blog and present their case in a proper forum
http://preciserf.com/about/

Meanwhile quit wasting the groups time with audiofool derived blather.

Quote
Regarding books covering RMS power, see my previous post citing the standard text for first year EEs in the USA, Hyatt and Kemmerly.  You might benefit from reading this basic Engineering text as it explains in detail how any waveform can be constructed from series of sine/cosine waves and how RMS values are used to calculate power.  Chapter 11 is where to start, if you have the engineering/mathematical background.

SSB, AM, QPSK...  RMS works for all of them.

Yes, Im fully aware of HAYT and Kemmerly and have Chapter 11 open in front of me. BTW, It is a second year book and covers what was part of a Second Class Electricians Mate or Electronics Technician manual; higher ratings got deeper into the math to what is in that book. I went thru a similar book when in college for EE and in the 80's when I went thru it again when I finally got time to complete the course.

You might want to review that chapter before commenting but its title "Sinusoidal Analysis" should give you a hint that it relates strictly to AC 60 Hz and has nothing to do with asynchronous waveforms as found with SSB and AM to keep it simple. In fact the authors point out that when referring to POWER in an AC circuit the term VA is used and is described as Apparent Power to eliminate confusion when comparing VA in a DC circuit as Average power. RMS Power is significant by its absence in that chapter which also states VA nor Effective Value is used in electronics and communications and the maximum value is the norm.....for obvious reasons I might add.

Again for obvious reasons hams are not required to jump thru the hoops of math far beyond their varied educations but a simple V x A is so simple as is a PEP Wattmeter which is FCC acceptable. Trying to falsely claim that RMS Power is in common use is the height of arrogance and in reality mostly used by a discredited subset of electronics similar to most CBers.

BTW, a steady RF carrier does not always mean a perfect sinewave either and Im sure several on here know why.

Carl


Title: RE: 1500 pep output max
Post by: K6BRN on January 17, 2016, 05:03:01 PM
Of course H&K chapter 11 applies to RF waveforms.  They are referred to as "communications applications" in the text.  This is a basic book with a chapter on general waveform theory that applies from near DC through microwave RF and beyond.  "Basic" seems pretty appropriate for this discussion.

And the suppliers of RF RMS power measurement devices are ... deluded?  As are their customers?

Be serious.  Please.

If you meant to say "I'm more comfortable simply talking about Average Power...", that's fine.  Because that's all that RMS power measurement tries to compute, indirectly.  No need to change the engineering curriculum.


Title: RE: 1500 pep output max
Post by: K6BRN on January 17, 2016, 05:16:02 PM
By the way... Chapter 11 in my (admittedly ancient) copy of H&K is titled:  Average Power and RMS Values", 1978 edition, BTW.


Title: RE: 1500 pep output max
Post by: KM1H on January 17, 2016, 06:12:04 PM
Quote
Of course H&K chapter 11 applies to RF waveforms.  They are referred to as "communications applications" in the text.  This is a basic book with a chapter on general waveform theory that applies from near DC through microwave RF and beyond.  "Basic" seems pretty appropriate for this discussion.

You hired on as a rewrite specialist? "applications" isnt included. A book aimed at 2nd year EE students is far from basic as is a good part of the math.

Try reading it again a few times before repeating erroneous statements.
Also try and stick to Chapter 11 as youre the one that keeps bringing it up. Quit drifting as a way to confuse folks.

Quote
By the way... Chapter 11 in my (admittedly ancient) copy of H&K is titled:  Average Power and RMS Values", 1978 edition, BTW.

Of course it is as it often includes RMS Current and Voltage VALUES but refuses to use RF Power for the reason stated plus it is all about 60Hz power.
Here, I'll make it easy for you:
Quote
Although we have succeeded in eliminating the factor of one-half from
our average-power relationships, we must now take care to determine
whether a sinusoidal quantity is expressed in terms of its maximum value
or its effective value. In practice, the effective value is usually used in the fields of power transmission or distribution and of rotating machinery;
in the areas of electronics and communications, the maximum value is more often used.[/b

If youre going to continue commenting get it correct at least please and practice reading comprehension.

Quote
Be serious.  Please.

At least I AM and possibly unlike others I have the book open to keep you honest......

Quote
And the suppliers of RF RMS power measurement devices are ... deluded?  As are their customers?

Who knows; a lot of stuff in magazines and ads never reach production; there are a lot of dreamers out there. I havent seen any nor reviews. Maybe in some esoteric and complex wave form they have some value.  But working at military and commercial millimeter wave and above RF for 10 years before retiring I never saw any mention of the elusive "RMS Power". My work included all the usual modulation schemes including the latest military radar, tracking, fire control disciplines to almost 300 gHz. My job was in R&D for a major DoD contractor.

Quote
If you meant to say "I'm more comfortable simply talking about Average Power...", that's fine.  Because that's all that RMS power measurement tries to compute, indirectly.  No need to change the engineering curriculum.

I meant what I said and
Quote
RMS power measurement tries to compute, indirectly
is as about as useless a statement Ive read in this thread.
Gee Mr FCC man I tried to compute my 1500W using light bulb loads and a light meter. What do you mean you measured 3500W with your Bird? I wanna see the calibration sticker!


Title: RE: 1500 pep output max
Post by: K6UJ on January 17, 2016, 06:36:23 PM
Quote
Of course H&K chapter 11 applies to RF waveforms.  They are referred to as "communications applications" in the text.  This is a basic book with a chapter on general waveform theory that applies from near DC through microwave RF and beyond.  "Basic" seems pretty appropriate for this discussion.

You hired on as a rewrite specialist? "applications" isnt included. A book aimed at 2nd year EE students is far from basic as is a good part of the math.

Try reading it again a few times before repeating erroneous statements.
Also try and stick to Chapter 11 as youre the one that keeps bringing it up. Quit drifting as a way to confuse folks.

Quote
By the way... Chapter 11 in my (admittedly ancient) copy of H&K is titled:  Average Power and RMS Values", 1978 edition, BTW.

Of course it is as it often includes RMS Current and Voltage VALUES but refuses to use RF Power for the reason stated plus it is all about 60Hz power.
Here, I'll make it easy for you:
Quote
Although we have succeeded in eliminating the factor of one-half from
our average-power relationships, we must now take care to determine
whether a sinusoidal quantity is expressed in terms of its maximum value
or its effective value. In practice, the effective value is usually used in the fields of power transmission or distribution and of rotating machinery;
in the areas of electronics and communications, the maximum value is more often used.[/b

If youre going to continue commenting get it correct at least please and practice reading comprehension.

Quote
Be serious.  Please.

At least I AM and possibly unlike others I have the book open to keep you honest......

Quote
And the suppliers of RF RMS power measurement devices are ... deluded?  As are their customers?

Who knows; a lot of stuff in magazines and ads never reach production; there are a lot of dreamers out there. I havent seen any nor reviews. Maybe in some esoteric and complex wave form they have some value.  But working at military and commercial millimeter wave and above RF for 10 years before retiring I never saw any mention of the elusive "RMS Power". My work included all the usual modulation schemes including the latest military radar, tracking, fire control disciplines to almost 300 gHz. My job was in R&D for a major DoD contractor.

Quote
If you meant to say "I'm more comfortable simply talking about Average Power...", that's fine.  Because that's all that RMS power measurement tries to compute, indirectly.  No need to change the engineering curriculum.

I meant what I said and
Quote
RMS power measurement tries to compute, indirectly
is as about as useless a statement Ive read in this thread.
Gee Mr FCC man I tried to compute my 1500W using light bulb loads and a light meter. What do you mean you measured 3500W with your Bird? I wanna see the calibration sticker!


Carl,

K6BRN persists even though he obviously has only a superficial understanding of this topic.  I think you are wasting your time with him.    ;D     
BTW, my Alpha 76PA you helped me here on the forum with, that had the arcing band switch on 160
is still trouble free.  thanks again !

73.
Bob
K6UJ


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 07:04:34 PM

...I would then refer them to an excellent presentation by an accredited expert...


Not fair.  I asked how YOU would do the derivations and explanations.  Not who you would choose to do it for you.  Your expert agrees with me on all the basic facts.  Except he doesn't mention the two logical interpretations of what is meant by the not-uncommonly used term "RMS power".  He just opines that it is technically incorrect to use it.  I suspect that may be why you picked his paper to do your homework for you...

If I had known there was such a politically charged obsession with that term here, I would have spelled out the first interpretation of "power derived from RMS data" earlier.  In my opinion, it should have been obvious from context.

I think we've identified the trolls in this thread.

Move on.



Title: RE: 1500 pep output max
Post by: K6AER on January 17, 2016, 08:20:52 PM
This has been an interesting read. I would almost guess most folks do not own a lab grade spectrum analyzer. If one cycle of the 14,000,000 cycles per second, being modulated on a 20 meter signal is higher than all the rest, that is your PEP signal level. That is all the FCC cares about. It does not care about power density. When checking for power level we set the analyzer for max signal hold. The FCC does not care a whit about duty cycle when it comes to maximum power.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 08:27:24 PM
This has been an interesting read. I would almost guess most folks do not own a lab grade spectrum analyzer. If one cycle of the 14,000,000 cycles per second, being modulated on a 20 meter signal is higher than all the rest, that is your PEP signal level. That is all the FCC cares about. It does not care about power density. When checking for power level we set the analyzer for max signal hold. The FCC does not care a whit about duty cycle when it comes to maximum power.

Thanks AER.  In other words, the shape and distortion of the (time domain) envelope on either side of that one cycle are irrelevant to the power measurement.


Title: RE: 1500 pep output max
Post by: K4KYV on January 17, 2016, 09:15:47 PM
Regarding books covering RMS power, see my previous post citing the standard text for first year EEs in the USA, Hyatt and Kemmerly.  You might benefit from reading this basic Engineering text as it explains in detail how any waveform can be constructed from series of sine/cosine waves and how RMS values are used to calculate power.

Yes, I am aware of that.  It's called "Fourier Transform".  Here is an animated graphical representation that clearly illustrates the example of a square wave, showing how it is composed of the fundamental sine wave frequency plus a series of sine wave odd harmonics. I just wish we had had easy access to this kind of animation back in the pre-internet days while I was in university when we had to mentally animate a still image printed on the pages of a textbook.
https://en.wikipedia.org/wiki/Fourier_series

 RMS values are used to calculate average power.  Vrms × Irms = Pavg

Vavg × Iavg is not a physically significant quantity of power.  Nor is calculating the RMS value of a varying level of power. RMS is useful as a voltage level or a current indication.  Its physical significance is that the RMS voltage (or current) is the equivalent value of DC current or voltage that would produce the same heating effect through a resistance as the a.c. waveform.

Quote
Regarding precise terminology, mean power and average power are two very different metrics.  Please look up the definitions of "Mean" and "Average".  They are not the same at all.

True, "mean" has more than one definition. Of a varying quantity (one example being alternating current), you can calculate a quadratic mean, harmonic mean, geometric mean or the arithmetic mean. The latter is the one that is the same thing as the average. RMS is an example of the quadratic mean, defined as the square root of the arithmetic mean of the squares of a set of numbers. Thus, the average is the arithmetic mean of of a set of numbers, taken to the 1st power, i.e. not squared, cubed, etc.

With alternating current, you have to be careful when you talk about the average value. Mathematically, the average value of an a.c. voltage or current is zero, by definition. Strictly speaking, we must specify the average absolute value of voltage or current, IOW the numerical average of the number, ignoring the polarity. A clear example of the absolute value of an a.c. waveform can be seen as the display of the unfiltered output of a full-wave rectifier as seen on an oscilloscope.

Here is a simple, non-mathematical explanation of the difference between average and mean:
http://www.differencebetween.net/science/difference-between-average-and-mean/

Quote
, AM, QPSK...  RMS works for all of them.
Yes, the RMS voltage or current. But when we multiply those two quantities together, we get average (= mean) power, not something called RMS power.

But again, we have to once again be careful. With a.c., power = voltage times current only when the voltage and current are precisely in phase. If V and I are out of phase, the result is not the true power.  That's why with alternating current another consideration is the power factor. PF = 1.0 when V and I are exactly in phase.  This explains why transformers are usually rated in V-A (volt-amperes), not watts.

Your Hammy Hambone wattmeter is accurate only when you are working it into a specified non-reactive load (usually 50 ohms), meaning that the power factor is 1.0.  Again, the 'wattmeter' does not measure watts at all; it measures voltage (normally average or mean voltage). A diode rectifier type meter does not measure RMS voltage. It can accurately measure a pure, steady,sine-wave carrier such as FM or key-down CW. With SSB, the "average" power reading will be inaccurately low. That's one of the reasons why the FCC chose not to use average power as the standard for the legal limit. OTOH, a thermocouple RF ammeter is a true RMS-reading instrument, and its reading can be used to calculate average power. Problem is, it is too sluggish to read short-duration peaks.


If I had known there was such a politically charged obsession with that term here, I would have spelled out the first interpretation of "power derived from RMS data" earlier.  In my opinion, it should have been obvious from context.

That would have less confusing, since "power derived from RMS data" is merely a description of how average or mean power is calculated. "RMS" anything is a characteristic of a continuously varying quantity, obtained by taking the mean of the squares of the instantaneous values during a cycle. With voltage, it is equal to the value of the direct current that would produce the same power dissipation in a resistive load. With power, one could perform a calculation by taking the mean of the squares of the instantanous values of power during a cycle, but this would be a futile, useless endeavour, because the value produced by the calculation would not represent the same dissipation in a resistive load as a direct current delivering that same quantity of power.

Furthermore, "power derived from RMS data" is not the same quantity as "RMS power". Such short-cuts in language are an example of intellectual laziness that should be avoided, because one cannot assume that the reader will find it to be obvious what you really meant to say. In science and engineering it is imperative that language be precise.



Title: RE: 1500 pep output max
Post by: QRP4U2 on January 17, 2016, 09:36:14 PM
Here is a simple math expression and explanation for average Power of a Sine wave voltage across a non-reactive resistance:

The average power dissipated in a pure (non-reactive) resistor R is, P = <v^2(t)>/ R.

<v^2(t)> is the value of v^2(t) averaged over time.

<v^2(t)> is called the "RMS" value of a voltage.

Thus, Average Power P = (Vrms)^2/R

Vrms is equal to the DC voltage that would cause R to dissipate the same power. Vrms is also equal to Vpeak x 0.707, or 0.3535 x Vpeak-to-Peak.

Average power also = Irms x Vrms also = Irms^2 x R.

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: WB4JTR on January 17, 2016, 10:28:27 PM
Furthermore, "power derived from RMS data" is not the same quantity as "RMS power"

"Power derived from RMS data" is the first logical interpretation of the words "RMS power" in the electrical context.  If that interpretation is intended, then "power derived from RMS data" IS the same quantity as "RMS power".

The second logical interpretation of the words "RMS" and "power" strung together is out of context in a discussion of basic electrical science.  But if this interpretation is intended it IS the same quantity as the "RMS power" discussed in your cut-and-paste below.  What the author of that text failed to mention is:  That second interpretation DOES have a place in statistical analysis describing the quality (as opposed to the quantity) of power delivered.

So both logical interpretations of the word string "RMS power" exist in the real world and are useful to the less politically obsessed, each in their own context.

Your C&P: "With power, one could perform a calculation by taking the mean of the squares of the instantanous values of power during a cycle, but this would be a futile, useless endeavour, because the value produced by the calculation would not represent the same dissipation in a resistive load as a direct current delivering that same quantity of power."

.


Title: RE: 1500 pep output max
Post by: W9IQ on January 18, 2016, 06:11:01 AM
This thread is losing visibility of the forest due to the trees.

FCC Part 97 defines PEP power as:

Quote
The average power supplied to the antenna transmission line by a transmitter during one RF cycle at the crest of the modulation envelope taken under normal operating conditions.

Note the use of the term average power.

For an AC signal applied to a purely resistive load, Average Power = IRMS*VRMS. This applies regardless of the waveform shape factor. Ohm's law can also be used in this case so that Average Power is VRMS2/R and also IRMS2*R.

Note the:

Quote
one RF cycle at the crest of the modulation envelope
.

Clearly, the measurement is for a single RF cycle and specifically the highest amplitude RF wave that can be found during normal operating conditions. Thus the term PEP - average power of the single RF cycle with the maximum amplitude.

For hams who are mere mortals, you can safely assume that your RF signal is a pure sine wave (the rest have the laboratory equipment to measure the exact RMS values regardless of the shape factor and can educate the FCC during a station inspection).

You can observe the peak to peak voltage of your transmitter into the feedline with an oscilloscope that has sufficient bandwidth. This peak to peak value, multiplied by 0.3536 is the RMS voltage. Square the RMS voltage, divide it by the resistance at your transmission line, and you have the PEP of your transmitter as defined by the FCC regulations. Note again that this (reasonably) assumes a pure sine wave and a purely resistive transmission line. The VEC question pool contains a question that requires application of this formula.

The oscilloscope is one means of measurement. It is also possible to build a peak detection circuit coupled with a small microprocessor to derive and directly display the PEP.

- Glenn W9IQ



Title: RE: 1500 pep output max
Post by: WB4JTR on January 18, 2016, 06:28:32 AM
This thread is losing visibility of the forest due to the trees.

FCC Part 97 defines PEP power as:

Quote
The average power supplied to the antenna transmission line by a transmitter during one RF cycle at the crest of the modulation envelope taken under normal operating conditions.

Note the use of the term average power.

For an AC signal applied to a purely resistive load, Average Power = IRMS*VRMS. This applies regardless of the waveform shape factor. Ohm's law can also be used in this case so that Average Power is VRMS2/R and also IRMS2*R.

Note the:

Quote
one RF cycle at the crest of the modulation envelope
.

Clearly, the measurement is for a single RF cycle and specifically the highest amplitude RF wave that can be found during normal operating conditions. Thus the term PEP - average power of the single RF cycle with the maximum amplitude.

For hams who are mere mortals, you can safely assume that your RF signal is a pure sine wave (the rest have the laboratory equipment to measure the exact RMS values regardless of the shape factor and can educate the FCC during a station inspection).

You can observe the peak to peak voltage of your transmitter into the feedline with an oscilloscope that has sufficient bandwidth. This peak to peak value, multiplied by 0.3536 is the RMS voltage. Square the RMS voltage, divide it by the resistance at your transmission line, and you have the PEP of your transmitter as defined by the FCC regulations. Note again that this (reasonably) assumes a pure sine wave and a purely resistive transmission line. The VEC question pool contains a question that requires application of this formula.

The oscilloscope is one means of measurement. It is also possible to build a peak detection circuit coupled with a small microprocessor to derive and directly display the PEP.

- Glenn W9on

Good summary, Glenn.  Thanks.

For the rest of the "debaters" here I will say:
A subject is exhausted when discussion devolves to debating the "words" used instead of the substance of the issue.  You may keep trolling on, throwing snippets cut-and-pasted from internet articles at each other ... But I have mostly lost interest at this point.

Again:  Move on.

qrt


Title: RE: 1500 pep output max
Post by: W5HRO on January 18, 2016, 07:29:46 AM
RMS power measurements and average/mean power measurements are not 100% exactly the same. They are very very close though.

It's like when you use an old thermocouple RF ammeter to measure your power and when you modulate it generally will rise up, but just a tiny bit. That tiny bit it rises is the RMS value, but those old thermocouple meters are not really that accurate when they measure that rise.


Title: RE: 1500 pep output max
Post by: W9IQ on January 18, 2016, 08:02:21 AM
Quote
It's like when you use an old thermocouple RF ammeter to measure your power and when you modulate it generally will rise up, but just a tiny bit. That tiny bit it rises is the RMS value, but those old thermocouple meters are not really that accurate when they measure that rise.

Brian,

You didn't mention the modulation technique but what you observed is most likely a function of the measuring instrument. Such an instrument measures average power (heat generated) but with a slow response time to changing power levels due to the thermal and meter latency. Thus if you take an un-modulated AM transmitter that is putting out 100 watts and measure it with your thermocouple meter, you will measure 100 watts (this is both the average power and the PEP at this point). But if you now modulate your AM signal at 100%, you would over some short measurement time see that your thermocouple meter reads 150 watts (average power / heat generated) while the transmitter is putting out 400 watts PEP.

The problem is that your modulation is probably not at 100% for a long enough period of time for the thermocouple meter to to fully respond. So voice/music peaks will blip the thermocouple meter slightly. All a function of the slow response (dampening) of a thermocouple type meter - not a result of average vs RMS, etc.

- Glenn W9IQ


Title: RE: 1500 pep output max
Post by: W5HRO on January 18, 2016, 09:06:19 AM
Brian,

You didn't mention the modulation technique but what you observed is most likely a function of the measuring instrument. Such an instrument measures average power (heat generated) but with a slow response time to changing power levels due to the thermal and meter latency. Thus if you take an un-modulated AM transmitter that is putting out 100 watts and measure it with your thermocouple meter, you will measure 100 watts (this is both the average power and the PEP at this point). But if you now modulate your AM signal at 100%, you would over some short measurement time see that your thermocouple meter reads 150 watts (average power / heat generated) while the transmitter is putting out 400 watts PEP.

The problem is that your modulation is probably not at 100% for a long enough period of time for the thermocouple meter to to fully respond. So voice/music peaks will blip the thermocouple meter slightly. All a function of the slow response (dampening) of a thermocouple type meter - not a result of average vs RMS, etc.

No, a sustained modulated tone on AM will make an old thermocouple ammeter rise up and stay there. It will only rise up a very tiny bit, but it is closer to what the true modulated RMS value actually is and it is not PEP.

And as you stated, those old meters only work from the heat being generated so they cannot not produce a fully accurate RMS reading for that reason.


Title: RE: 1500 pep output max
Post by: K4KYV on January 18, 2016, 10:59:48 AM
Quote
It's like when you use an old thermocouple RF ammeter to measure your power and when you modulate it generally will rise up, but just a tiny bit. That tiny bit it rises is the RMS value, but those old thermocouple meters are not really that accurate when they measure that rise.

Brian,

You didn't mention the modulation technique but what you observed is most likely a function of the measuring instrument. Such an instrument measures average power (heat generated) but with a slow response time to changing power levels due to the thermal and meter latency. Thus if you take an un-modulated AM transmitter that is putting out 100 watts and measure it with your thermocouple meter, you will measure 100 watts (this is both the average power and the PEP at this point). But if you now modulate your AM signal at 100%, you would over some short measurement time see that your thermocouple meter reads 150 watts (average power / heat generated) while the transmitter is putting out 400 watts PEP.

The problem is that your modulation is probably not at 100% for a long enough period of time for the thermocouple meter to to fully respond. So voice/music peaks will blip the thermocouple meter slightly. All a function of the slow response (dampening) of a thermocouple type meter - not a result of average vs RMS, etc.
The rise in reading on a thermocouple meter with modulation is perfectly accurate when the modulation source is a sustained sine wave tone, but with sources such as voice or music it is difficult to surmise any meaning out of the upward kick.

When a thermocouple rf ammeter or other true RMS-reading instrument is used to measure the line current at the output of an AM transmitter, modulating with a pure sine wave tone to 100% modulation produces a 22.5% rise in reading, assuming the modulated stage is perfectly linear and that the modulator doesn't cause a sag in power supply voltage, IOW, assuming no "carrier shift". With normal program content having peaks at 100%, the rise is much less, because the average power of a voice waveform is much less than that of a sine wave.  BC engineers usually wait for a quiet passage in the program material to take base current meter readings, and I have even heard of stations having a cut-off switch at the tower that temporarily disables the audio feeding the transmitter long enough to take a reading.

An average-reading diode rectifier type instrument can be useful with full-carrier AM.  The meter scale is calibrated to read RMS line current, and is accurate as long as it is reading a steady unmodulated carrier. Its normal disadvantage can now be used to advantage in this application, because with AM, the average rf current reading remains steady and does not rise with modulation.  Any variation in reading with modulation indicates undesirable carrier shift.  The explanation for this is simple; with modulation applied, the average current does not change because the net change resulting from positive and from negative modulation peaks is zero.  Now, keep in mind that we are talking about average current, not average power here.  In this case, the meter reading with the scale calibrated in watts (average) instead of amps becomes erroneous when modulation is applied; it simply ignores the modulation. This turns out to be highly desirable for taking tower base current readings, since the engineer does not have to wait for a silent period in the program material, or else disable the audio feeding the modulator, long enough to take a reading.

In practical terms, that means an accurately calibrated Bird 43 wattmeter set to read "average" power would be an excellent instrument for reading the carrier output of an AM transmitter working into a non-reactive 50-ohm load, just as it would for an FM, RTTY (Baudot) or key-down CW transmitter working into that same load.  But such a meter would be useless for reading the average output power from a SSB transmitter.

"Power derived from RMS data" is the first logical interpretation of the words "RMS power" in the electrical context.  If that interpretation is intended, then "power derived from RMS data" IS the same quantity as "RMS power"... So both logical interpretations of the word string "RMS power" exist in the real world and are useful to the less politically obsessed, each in their own context.
Except, THERE IS NO SUCH THING as "RMS power". If you insist on using that erroneous term,  go ahead and bask in your smug ignorance and let knowledgeable readers just consider the source.

For the rest of the "debaters" here I will say:
A subject is exhausted when discussion devolves to debating the "words" used instead of the substance of the issue.  You may keep trolling on, throwing snippets cut-and-pasted from internet articles at each other ... But I have mostly lost interest at this point... qrt

Good!





Title: RE: 1500 pep output max
Post by: W1BR on January 18, 2016, 11:02:40 AM
A thermo converter is not able to read true RMS power???


Title: RE: 1500 pep output max
Post by: K7KBN on January 18, 2016, 11:39:07 AM
When do we get to "Bird Watts?" ;D


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 18, 2016, 02:04:51 PM
Quote
A thermo converter is not able to read true RMS power???

Again, it is not RMS power, as the only correct, physically meaningful term is, "Average Power."

Quote from: Roy Lewallen, developer of EZNEC

RMS is a mathematical function, like average, that reduces a complex function to a single value. And, like average, it has a precise definition. The definition is revealed by the name – it’s the square Root of the Mean of the Square of the function....The RMS value of power is not the equivalent heating power and, in fact, it doesn’t represent any useful physical quantity. The RMS and average values of nearly all waveforms are different.



Title: RE: 1500 pep output max
Post by: W1BR on January 18, 2016, 02:30:53 PM
Quote
A thermo converter is not able to read true RMS power???

Again, it is not RMS power, as the only correct, physically meaningful term is, "Average Power."

Quote from: Roy Lewallen, developer of EZNEC

RMS is a mathematical function, like average, that reduces a complex function to a single value. And, like average, it has a precise definition. The definition is revealed by the name – it’s the square Root of the Mean of the Square of the function....The RMS value of power is not the equivalent heating power and, in fact, it doesn’t represent any useful physical quantity. The RMS and average values of nearly all waveforms are different.



Agreed.  RMS was incorrectly stated,  But, it was in response to this post so it is bit out of context:

And as you stated, those old meters only work from the heat being generated so they cannot not produce a fully accurate RMS reading for that reason.


Title: RE: 1500 pep output max
Post by: K4KYV on January 18, 2016, 02:37:38 PM
Quote from: Roy Lewallen, developer of EZNEC

Quote
RMS is a mathematical function, like average, that reduces a complex function to a single value. And, like average, it has a precise definition. The definition is revealed by the name – it’s the square Root of the Mean of the Square of the function....The RMS value of power is not the equivalent heating power and, in fact, it doesn’t represent any useful physical quantity. The RMS and average values of nearly all waveforms are different.

Exactly what I have been trying to say.



Title: RE: 1500 pep output max
Post by: QRP4U2 on January 18, 2016, 03:06:43 PM
Quote from: WB4JTR
...For the rest of the "debaters" here I will say:
A subject is exhausted when discussion devolves to debating the "words" used instead of the substance of the issue.

Words have precise meanings, especially when discussing topics in Mathematics, Physics, and Engineering.

If this subject has devolved, it is due to the misunderstanding of established physical principles.  

Phil


Title: RE: 1500 pep output max
Post by: W1BR on January 18, 2016, 03:56:07 PM
Well, I am a bit confused as to why a thermal converter is not an accurate method for measuring RF power.  My Boonton milliwattmeter is based on thermal heating.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 18, 2016, 04:24:02 PM
Well, I am a bit confused as to why a thermal converter is not an accurate method for measuring RF power.  My Boonton milliwattmeter is based on thermal heating.

I don't think anyone is saying that.

As Clint Eastwood said, "An instrument has to know its limitations," or some such.  :)

For a constant carrier, and properly calibrated, it should be accurate.

Since a thermal converter has mass, it takes a finite amount of time for it to reach thermal equilibrium, a thermal time constant if you will.

For an RF input such as SSB, the carrier power varies widely and probably quicker than the thermal time constant of the sensor. So this would probably be the only limitation to accuracy.

However, if the sensor is in a fairly well insulated environment, and the surrounding material constants are known, it could be very accurate.


https://www.rogerscorp.com/documents/1526/acs/Temperature-Rise-Estimations-in-Rogers-High-Frequency-Circuit-Boards-Carrying-Direct-or-RF-Current.pdf

Phil


Title: RE: 1500 pep output max
Post by: W1BR on January 18, 2016, 05:00:20 PM
OK. I may have read a comment and interpreted it wrong.


Title: RE: 1500 pep output max
Post by: W5HRO on January 18, 2016, 05:15:02 PM
Quote from: WB4JTR
...For the rest of the "debaters" here I will say:
A subject is exhausted when discussion devolves to debating the "words" used instead of the substance of the issue.

Words have precise meanings, especially when discussing topics in Mathematics, Physics, and Engineering.

If this subject has devolved, it is due to the misunderstanding of established physical principles.  

Phil

How many Polocks does it take to screw in a lightbulb?


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 18, 2016, 07:36:43 PM
Quote from: WB4JTR
...For the rest of the "debaters" here I will say:
A subject is exhausted when discussion devolves to debating the "words" used instead of the substance of the issue.

Words have precise meanings, especially when discussing topics in Mathematics, Physics, and Engineering.

If this subject has devolved, it is due to the misunderstanding of established physical principles.  

Phil

How many Polocks does it take to screw in a lightbulb?

By my calculations it takes about 12.5 HRO's to screw in a lightbulb.


Title: RE: 1500 pep output max
Post by: W5HRO on January 18, 2016, 09:05:28 PM
By my calculations it takes about 12.5 HRO's to screw in a lightbulb.

So far I count 3. Don, Carl and you from the cheap seats. The world was proven not to be flat a long time ago.

http://www.linear.com/product/LTC5583


Title: RE: 1500 pep output max
Post by: KB8E on January 19, 2016, 04:46:27 AM
I'm not sure why Linear Technology labels the LTC5583 an rms power detector. According to the data sheet, the IC can output the envelope of high crest factor waveforms and can be used to determine average power with various time constants including the power at the peak of the envelope i.e. PEP. I'm inferring that the use of the term "rms power detector" implies true average power and NOT rms power. If the device were fast enough to follow the actual RF carrier, not just its envelope, it could show instantaneous power. In my opinion, an unfortunate choice of words on Linear Technology's part. It just adds more confusion to be brought up as part of this discussion. Fortunately, there are those in this string that know what they are talking about and are attempting to add understanding to the incorrect use of the term rms power; it exists and can be calculated, but is of no practical significance and can't, to my knowledge, be directly measured.

Sam


Title: RE: 1500 pep output max
Post by: W6RZ on January 19, 2016, 04:53:27 AM
Here's a pretty good article describing how chips like the LTC5583 work.

http://www.digikey.com/en/articles/techzone/2014/feb/rf-power-measurement-using-rms-detectors


Title: RE: 1500 pep output max
Post by: KB8E on January 19, 2016, 05:07:40 AM
I've actually used the LTC5583 in a design. Because it can accurately follow the power envelope of an RF waveform, it can be used as a power detector that is accurate over a fairly large dynamic range. This works well for amplifier foldback with high-VSWR loads and for accurate power measurements itself since the chip yields power readings directly. A nice part with a confusing description.

Sam


Title: RE: 1500 pep output max
Post by: W5HRO on January 19, 2016, 05:51:21 AM
Because it can accurately follow the power envelope of an RF waveform, it can be used as a power detector that is accurate over a fairly large dynamic range.

See, that's what separates it out as an RMS power detector and not an Average/Mean power detector. Average/Mean power detectors will NOT follow the envelope properly. It they do then they are not true Average/Mean power detectors. Average/Mean power is based on a simple set of know values and from a perfect sinewave. It’s basically a quick and dirty measurement. I most cases is will be close enough, but it is never exact. That’s why a true RMS power measurement is better.

That's actually been the whole point of this discussion and is exactly why I jumped into it. It's about how to properly follow and measure the evevolope.

It's a shame we don't make a version designed for the lower frequencies, but there just wouldn’t be any money in it. The volume would be too small.


Title: RE: 1500 pep output max
Post by: W6RZ on January 19, 2016, 06:04:28 AM
The LTC5581 goes down to 10 MHz. It does not have an envelope function.

http://www.linear.com/product/LT5581


Title: RE: 1500 pep output max
Post by: KB8E on January 19, 2016, 06:33:27 AM
The data sheet actually refers to the outputs as envelope outputs. What these outputs show is the power envelope normalized to a longer-term average power value. The averaging period of the envelope outputs is affected by an external capacitor.

Sam




Title: RE: 1500 pep output max
Post by: W6RZ on January 19, 2016, 06:48:25 AM
The data sheet actually refers to the outputs as envelope outputs. What these outputs show is the power envelope normalized to a longer-term average power value. The averaging period of the envelope outputs is affected by an external capacitor.

Sam

Are you referring to the LTC5583 or LTC5581?


Title: RE: 1500 pep output max
Post by: W5HRO on January 19, 2016, 06:57:29 AM
The LTC5581 goes down to 10 MHz. It does not have an envelope function.

Does it go down to the lower HF bands like 40 and 80-meters or down into the MF region where it could be used in BC power meter designs ::) And also what the other guy just said about the envelope, but the term envelope is just a reference to the RF envelope whether is contains intelligence or not. It doesn’t matter.

If you have ever been around any of the modern cell phone repair stations all of their power measurement equipment is in RMS now.

Anyway, you can keep trying to dispute this anyway way you want, but the earth isn’t flat.




Title: RE: 1500 pep output max
Post by: WB4JTR on January 19, 2016, 07:48:45 AM
By my calculations it takes about 12.5 HRO's to screw in a lightbulb.

So far I count 3. Don, Carl and you from the cheap seats. The world was proven not to be flat a long time ago.

http://www.linear.com/product/LTC5583

As much as I would like to gloat over Linear's use of "RMS power detector" for the LTC5583 and claim some silly "victory", the fact is it parses differently than the isolated fragment "RMS power".  The descriptors "RMS" and "power" both apply to the noun "detector", not to each other.

There should be no objection to it or phrases like "RMS power measurement".  (But there probably will be -- who knows?)

No, the "terminology police" are going to have to make peace with the fragment "RMS power" used in context, or just continue their campaign to eradicate it from the face of the earth.

" No soup! ...Next..."

Again:  qrt


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 19, 2016, 08:13:54 AM
I'm not sure why Linear Technology labels the LTC5583 an rms power detector. According to the data sheet, the IC can output the envelope of high crest factor waveforms and can be used to determine average power with various time constants including the power at the peak of the envelope i.e. PEP. I'm inferring that the use of the term "rms power detector" implies true average power and NOT rms power. If the device were fast enough to follow the actual RF carrier, not just its envelope, it could show instantaneous power. In my opinion, an unfortunate choice of words on Linear Technology's part. It just adds more confusion to be brought up as part of this discussion. Fortunately, there are those in this string that know what they are talking about and are attempting to add understanding to the incorrect use of the term rms power; it exists and can be calculated, but is of no practical significance and can't, to my knowledge, be directly measured.

Sam

That was my take as well.

Phil


Title: RE: 1500 pep output max
Post by: KB8E on January 19, 2016, 08:25:31 AM
Lee,

I'm going to bow out of this discussion as well. Just a few final thoughts:

1. The LTC devices and others like it by other vendors appear to calculate internally the rms value of the incoming RF waveform and then average and scale the result, sometimes with normalization. The vendor's applications notes contain very nice descriptions on how they work and their limitations. Good reading!

2. The concept of rms power may have been complicated by its use in the audio community. There, rms power refers to continuous, average power with no connection to rms except in converting sinewave voltage to average power. See the Wikipedia article on audio power and the references for good explanations on power measurements and (incorrect) nomenclature. I've designed and built my own audio power amplifiers (solid state) and appreciate the concept of continuous average power, but don't like the term often used to express it i.e. rms power.

3. Although PEP is defined as the average power over one RF cycle at the peak of the envelope, due to the fact that the modulation bandwidth is much, much less than the carrier frequency, finding that one peak cycle is not an issue in real life. Compared to the RF cycle, the envelope peak is very broad. This was shown quite well with scope plots earlier. PA clipping can change this somewhat, especially in solid state amplifiers, but realistically, not enough to worry about.

4. As I've stated before, there are good, knowledgeable people e.g. Lee, Phil, others on this thread that know what they are talking about. Their input is appreciated, at least by me.

Regards,

Sam


Title: RE: 1500 pep output max
Post by: W5HRO on January 19, 2016, 12:54:36 PM
As much as I would like to gloat over Linear's use of "RMS power detector" for the LTC5583 and claim some silly "victory", the fact is it parses differently than the isolated fragment "RMS power".  The descriptors "RMS" and "power" both apply to the noun "detector", not to each other.

There should be no objection to it or phrases like "RMS power measurement".  (But there probably will be -- who knows?)

No, the "terminology police" are going to have to make peace with the fragment "RMS power", used in context, or just continue their campaign to eradicate it from the face of the earth.

" No soup! ...Next..."

Again:  qrt

Terminology Police, I like that  ;D

I only jumped in originally because of your one post I saw and I think part of the problem was it was just badly worded which made it really confusing. I will still never fully agree with using the PEP measurement method because it has the bad habit of misleading people. On AM for example even with 100% modulation and the human voice your voice peaks normally will stay well below what is considered the legal limit when your carrier level is at 375W, therefore you can run that carrier level up much higher provided your voice peaks are not excessive. However, you constantly get people that will argue that your carrier must be no more than 375W max and they will argue that to the death simply due to their own ignorance. It never fails. Switching to true RMS power measurements instead would work so much better and eliminate the confusion associated with PEP. It will never happen and the technology isn’t there yet across the board anyway, but it would still be a much better measurement approach. Some of the average reading meters out there usually work well enough, but they themselves are not 100% accurate either just like most of the cheap PEP meters that are usually a joke.

The RMS and Average/Mean power definitions are another issue and I gave up trying to explain it on these hams boards a long time ago, because the grumpy old men become even grumpier old men whenever it comes up and they always do exactly what they did here. The two main ones have been run off all of the other hams boards including mine, except for qrz and this one, but it’s probably only a matter of time before they disappear completely.

Anyway, this is where I bow out as well.

73’s…


Title: RE: 1500 pep output max
Post by: WB4JTR on January 19, 2016, 02:22:19 PM
Thanks Sam and Brian for the concise summaries.  I respect each of your positions and can agree with each and every point you've expressed.

I can't remember the lyrics to Kumbaya, but I will say:  Peace, brothers.

-Lee


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 19, 2016, 03:50:01 PM
Power control devices for transmitters transmitting quadrature amplitude (QUAM) and Time Division Multiplex Modulation (TDMA), as in cellular operations, need power detectors in order to control output where the crest factor (CF) is high. CF is the ratio of Peak-Power to Average-Power for time-varying signals.

The power detection and control for cellular systems transmitters necessarily has to operate very quickly and operate in the 250 MHz to 4 GHz range, so devices were designed to act very quickly on high Crest Factors in order to control power almost instantaneously.

A methodology to do this, and when implemented in a device which accomplishes this function, is called an RMS and Peak-to-Average Detector, and erroneously described by some as an, RMS Power Detector.

One of the internal functions implemented in this device is an RMS detector. The RMS detector's output signal is a signal proportional to the Logarithm of the TIME AVERAGED Input Voltage Squared..

So, an RMS Power Detector does NOT work on any RMS power principle, but uses a special RMS Detector to quickly control high Crest Factor waveforms. I.E, an RMS Power Detector uses a special RMS detection technique to derive voltage outputs from high frequency, fast time varying waveforms.

Had HRO and others studied the mathematics behind these detectors, they would have quickly seen they have an incorrect understanding of their own company's devices. Yet they continue to make ridiculous flat-earth and other off-topic statements in an attempt to obfuscate the issue.

"Well Pilgrim...."

BTW, Hittite Microwave Devices has straightforward explanations for these devices, not clouded in the alchemy language of LT.  

Phil - AC0OB





    


Title: RE: 1500 pep output max
Post by: W5HRO on January 19, 2016, 04:56:04 PM
Power control devices for transmitters transmitting quadrature amplitude (QUAM) and Time Division Multiplex Modulation (TDMA), as in cellular operations, need power detectors in order to control output where the crest factor (CF) is high. CF is the ratio of Peak-Power to Average-Power for time-varying signals.

The power detection and control for cellular systems transmitters necessarily has to operate very quickly and operate in the 250 MHz to 4 GHz range, so devices were designed to act very quickly on high Crest Factors in order to control power almost instantaneously.

A methodology to do this, and when implemented in a device which accomplishes this function, is called an RMS and Peak-to-Average Detector, and erroneously described by some as an, RMS Power Detector.

One of the internal functions implemented in this device is an RMS detector. The RMS detector's output signal is a signal proportional to the Logarithm of the TIME AVERAGED Input Voltage Squared..

So, an RMS Power Detector does NOT work on any RMS power principle, but uses a special RMS Detector to quickly control high Crest Factor waveforms. I.E, an RMS Power Detector uses a special RMS detection technique to derive voltage outputs from high frequency, fast time varying waveforms.

Had HRO and others studied the mathematics behind these detectors, they would have quickly seen they have an incorrect understanding of their own company's devices. Yet they continue to make ridiculous flat-earth and other off-topic statements in an attempt to obfuscate the issue.

"Well Pilgrim...."

BTW, Hittite Microwave Devices has straightforward explanations for these devices, not clouded in the alchemy language of LT.  

Phil - AC0OB

How many places around the web did you have to search and do copy and paste to patch all of that together?

CF is in fact the ratio of Peak-Power to Average-Power for time-varying signals and that's exactly what is being considered the RMS power value.

The fact you still don't get that is typical for the way this discussion has gone so keep trying...

Some people just have way too much time on their hands.

Later










Title: RE: 1500 pep output max
Post by: K4KYV on January 19, 2016, 05:33:57 PM
The two main ones have been run off all of the other hams boards including mine, except for qrz and this one, but it’s probably only a matter of time before they disappear completely.
I assume I am "one" of those.  No, I did NOT get run off your board.  You took it down after you felt offended that Rob K5UJ and I had dissed your precious plasma TV when we posted in a thread that those RFI-spewing pieces of garbage should be banned from the market, and the sooner the existing ones crap out, the better. So, when you decided to start it back up, all of your grand total of 75-80 members had to re-register or else let it slide.  I decided  to  do the latter, since I didn't think it was worth the bother, especially since you are the one posting most of the messages that appear on your own board.  As for the other one, I have not been "run off"; I am still a member but no longer post there because I don't wish to tolerate the smug self-righteous stuffed shirts that run it - exactly the same reason you have stated that you no longer post there.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 19, 2016, 05:59:59 PM

Quote
How many places around the web did you have to search and do copy and paste to patch all of that together?

CF is in fact the ratio of Peak-Power to Average-Power for time-varying signals and that's exactly what is being considered the RMS value.

The fact you still don't get that is typical for the way this discussion has gone so keep trying...

Some people just have way too much time on their hands.

Later

I don't have to cut and paste anything because, unlike you, I understand what I say and write.

For the record, I have never been kicked off of any website.

I voluntarily closed down my account on your website Brian, because anytime anyone disagreed with one of your inaccurate statements, you went into a tirade and wola, you had to suddenly reboot your website and wola, comments or threads posted from people with whom you disagreed simply disappeared.

Quote
The two main ones have been run off all of the other hams boards including mine, except for qrz and this one, but it’s probably only a matter of time before they disappear completely.

You might be, maybe, somewhat believed here if you could only get the facts straight.


Phil - AO0OB




Title: RE: 1500 pep output max
Post by: W5HRO on January 19, 2016, 06:27:12 PM
I assume I am "one" of those.  No, I did NOT get run off your board.  You took it down after you felt offended that Rob K5UJ and I had dissed your precious plasma TV when we posted in a thread that those RFI-spewing pieces of garbage should be banned from the market, and the sooner the existing ones crap out, the better. So, when you decided to start it back up, all of your grand total of 75-80 members had to re-register or else let it slide.  I decided  to  do the latter, since I didn't think it was worth the bother, especially since you are the one posting most of the messages that appear on your own board.  As for the other one, I have not been "run off"; I am still a member but no longer post there because I don't wish to tolerate the smug self-righteous stuffed shirts that run it - exactly the same reason you have stated that you no longer post there.

It had absolutely nothing to do with that Don or the topic you mentioned. You just wanted a place to ventilate and that was all which is apparent by the topics you also start on qrz.com now-a-days. I would think after all these years you would quit finding ways to keep complaining about the exact same topics over and over again. It's actually a good thing you never did come back. Carl did and I had to run him back off because of the way he is. Phil is a different story though. He always felt like he had to compete with me for whatever reason just like here. It's always been about EGOs with you guys and that's been the whole problem from the very beginning. You guys do the same garbage on every board you go to.

Anyway, none of that has anything to do with this topic. The crest factor is the peak amplitude of the waveform divided by the RMS value. Since you guys are now officially the "Terminology Police" then it's really PAPR, peak-to-average power ratio. For all practical purposes the industry is recoining term to RMS power because it’s a more accurate measurement of average power. So there, I answered your question from the other day, happy now?

Like I said some people just have way too much time on their hands.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 19, 2016, 08:04:08 PM
Quote
...The crest factor is the peak amplitude of the waveform divided by the RMS value...

Wrong again, El Brino, we're talking about real-time analog computation here and the final output of the chip, not your fantasies.

The output of the final signal is missing a natural logarithmic term, which means the final output voltage of the analog IC is providing a signal directly proportional to the instantaneous signal power, normalized to the average real power.

The average real power normalization is done by the RMS detector circuit.

This is not garbage or EGO, but technically correct facts.

Phil - AC0OB



Title: RE: 1500 pep output max
Post by: W5HRO on January 19, 2016, 08:29:32 PM
Quote
...The crest factor is the peak amplitude of the waveform divided by the RMS value...

Wrong again, El Brino, were talking about real-time analog computation here and the final output of the chip, not your fantasies.

The output of the final signal is missing a natural logarithmic term, which means the output of the detector is providing a signal directly proportional to the instantaneous signal power, normalized to the average real power.

The average real power normalization is done by the RMS detector circuit.

This is not garbage or EGO, but technically correct facts.

Phil - AC0OB

No, it's garbage and 100% pure because I was referring to what crest factor is and also PAPR and I wasn't referring to the chip.

So see, you just did exactly what I was referring to and again.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 19, 2016, 08:46:31 PM
Quote from: W5HRO


... http://www.linear.com/product/LTC5583...

I guess that wasn't you?


Title: RE: 1500 pep output max
Post by: W5HRO on January 19, 2016, 09:33:45 PM
Quote from: W5HRO


... http://www.linear.com/product/LTC5583...

I guess that wasn't you?

It was earlier [I was banned for a week for calling you this], but you took my last post directed at Don where I wasn't discussing the actual chip.

See , this is exactly the reason why I became fed up and deleted all of your posts that day which made you leave. You would constantly come into my topics and do exactly what you are doing here on this board with the same freaking attitude. Instead of contributing you were always contradicting and on purpose so I guess in a way I’m returning the favor now. After a couple months of putting up with it I did something about it and you still just don’t like it. Nobody else would have put up with it for as long as I did.

Anyway, we can just keep going here if you want and get this thread locked up or deleted because I’m going to start saying a hell of a lot more about you guys and its going to be way worse than what I have already said. It’s your choice because I simply don’t care.

Right now I’m going to bed because I have to go to work in the morning so we will continue this tomorrow if necessary.



Title: RE: 1500 pep output max
Post by: QRP4U2 on January 20, 2016, 10:45:25 AM
Quote from: KM1H

...I would first tell them to ignore everything you say as it is doing no good by deliberately splitting into warring factions which I suspect is your primary goal.

I would then refer them to an excellent presentation by an accredited expert on the subject and this paper he wrote.

http://www.dudleylab.com/Appnote-4-Power-tests1.pdf.


That reference is a very good presentation on Power and its measurements.

Phil - AC0OB



Title: RE: 1500 pep output max
Post by: W5HRO on January 20, 2016, 01:14:18 PM
That reference is a very good presentation on Power and its measurements.

All elementary stuff and the part where it says "The RMS value by itself is not the comparable heating power and it doesn’t correspond to any useful physical quantity; no heat, no power" is what guys like yourself use to make your case when people use the term RMS Power.

Now, if you go back through my posts you will find where I said you cannot really measure modulated RMS Power from heat when I was describing the old thermocouple ammeters. However, that modulated RMS value can be used to generate a much more accurate power measurement. The fact the industry is starting to call it RMS Power is insignificant. It only matters to jokers like you.

The issue here was mainly with the ITU paragraph and the posts regarding it. “PEP means the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope taken under normal operating conditions.” The other guys post was just badly worded and what he was trying to say just didn’t come out right at first so it made everything confusing especially when he threw the word harmonics in there with it. It even confused me at first because it sounded like he didn’t really know anything.

The issue that I have and have always had is that is only referes to one cycle and one cycle is what is also used to calculate Average/Mean power based on a set of predetermined values from a perfect symmetrical sinewave. Well, in the real world under normal operating conditions with voice communications for example that perfect symmetrical sinewave does not exist so most meters used to measure it (not PEP meters) basically preform a quick and dirty avg/mean measurement that is not 100% accurate. The crest of the modulation envelope should be quickly sampled all along the envelope at the different levels and at more than just one cycle to help generate a better overall average measurement to simulate real world operating conditions. I don’t consider such a measurement PEP and at the same time it’s not the old-style typical avg/mean power measurement either. The new term being coined in the industry for it is RMS Power whether you like it or not. You are going to start seeing it more and more so you’d better get a custom to it. It’s the same thing happing in the audio world and why you are seeing the term RMS Power often now because the crest factor and the peak-to-average power ratio (PAPR) are the same thing when referring to sound decibels in dB.

All I can say is that you don’t have to like it, but you’d better get used to it because that’s what’s coming and I happen to agree with it.


Title: RE: 1500 pep output max
Post by: W1BR on January 20, 2016, 01:19:48 PM
Just curious, but why wouldn't any single 360 degree RF cycle be other than sinusoidal  waveform if the plate tank has reasonable q?


Title: RE: 1500 pep output max
Post by: W5HRO on January 20, 2016, 01:30:28 PM
Just curious, but why wouldn't any single 360 degree RF cycle be other than sinusoidal  waveform if the plate tank has reasonable q?

The current reference is about a voice modulated RF envelope whether it is AM or SSB. The shape of that RF envelope will mirror the speech pattern.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 20, 2016, 01:44:20 PM
Just curious, but why wouldn't any single 360 degree RF cycle be other than sinusoidal  waveform if the plate tank has reasonable q?

If you are referring to the output of say, an LC resonant circuit containing two elements (L and C), or a three-element PI net or PI-L net circuit, you certainly could have a full sinusoidal waveform.

Take for example the output of a class E (switching) transmitter's circuit using a properly tuned filter. The output waveform will be a sinusoid.


Title: RE: 1500 pep output max
Post by: W1BR on January 20, 2016, 01:47:39 PM
Just curious, but why wouldn't any single 360 degree RF cycle be other than sinusoidal  waveform if the plate tank has reasonable q?

The current reference is about a voice modulated RF envelope whether it is AM or SSB. The shape of that RF envelope will mirror the speech pattern.
 

This is what I was The issue that I have and have always had is that is only referes to one cycle and one cycle is what is also used to calculate Average/Mean power based on a set of predetermined values from a perfect symmetrical sinewaveasking about:


Despite the confusing verbiage, the accuracy of a single RF cycle being perfectly sinusoidal would relate to the harmonic content, not the modulating waveform...  peak power would seem to be based the  maixma of the largest AC RF crest for a single RF cycle, not the modulating waveform.


Title: RE: 1500 pep output max
Post by: K4KYV on January 20, 2016, 01:55:15 PM
...All elementary stuff and the part where it says "The RMS value by itself is not the comparable heating power and it doesn’t correspond to any useful physical quantity; no heat, no power" is what guys like yourself use to make your case when people use the term RMS Power... It only matters to jokers like you.
Jokers? You mean to physicists and engineers.

Quote
Now, if you go back through my posts you will find where I said you cannot really measure modulated RMS Power from heat when I was describing the old thermocouple ammeters.
True, because the thermocouple meter can't measure a quantity that doesn't exist.  The thermocouple meter measures RMS current, not power. That current indication, using Ohm's law, is used to calculate power; that power is the average or mean power.

Quote
However, that modulated RMS value can be used to generate a much more accurate power measurement.
Exactly what I just said (see above).
Quote
The fact the industry is starting to call it RMS Power is insignificant.
If what you say is true, it's significant only in that marketing has triumphed over physics and engineering. Who or what is "the industry"?

Quote
The issue here was mainly with the ITU paragraph and the posts regarding it. “PEP means the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope taken under normal operating conditions.”
What are you trying to argue anyway, "RMS power" vs average/mean power, or PEP vs average/mean power? Two different topics.

Quote
The issue that I have and have always had is that is only refers to one cycle and one cycle is what is also used to calculate Average/Mean power based on a set of predetermined values from a perfect symmetrical sinewave.
That's a point worth pondering. Take an AM signal, for instance. You have the carrier, upper sideband and lower sideband. So where do you  get that "one cycle"? A spectrum analyser clearly displays the carrier, which is head and  shoulders above the maximum amplitude of any component of the USB or LSB.  That definition suggests the old thought, back in the 1920s when it was being debated whether or not sidebands exist as physical reality, or only in the mathematics that describe the modulation process. To the latter school of thought, the carrier actually increased and decreased in amplitude in step with the modulation. How else would you come up  with that "one cycle" business? To-day, that would be explained in terms of time domain (display of the envelope pattern on an oscilloscope) vs frequency domain (display on a spectrum analyser or panadaptor).

Quote
Well, in the real world under normal operating conditions with voice communications for example that perfect symmetrical sinewave does not exist so most meters used to measure it (not PEP meters) basically preform a quick and dirty avg/mean measurement that is not 100% accurate. The crest of the modulation envelope should be quickly sampled all along the envelope at the different levels and at more than just one cycle to help generate a better overall average measurement to simulate real world operating conditions. I don’t consider such a measurement PEP and at the same time it’s not the old-style typical avg/mean power measurement either.
The old fashioned thermocouple meter is the simplest instrument capable of measuring true RMS current. The problem is, the thermocouple has thermal inertia which causes it to be too sluggish to measure short duration peaks, like the crest of a modulation envelope. But it does accurately measure the RMS value of a sustained current, regardless of waveform.  The 22.5% increase in reading with 100% tone modulation of an AM transmitter indicates a 50% increase in power: average/mean power, not a non-existent RMS power nor peak envelope power.  Read the specs from Bird on the APR-16 average power meter (see the link in a previous post), and they will tell you that the instrument is incapable of measuring the average power of a modulated AM signal.

 
Quote
The new term being coined in the industry for it is RMS Power whether you like it or not. You are going to start seeing it more and more so you’d better get a custom to it.
 What "the industry" and marketers say does not make it a scientific reality.
Quote
All I can say is that you don’t have to like it, but you’d better get used to it because that’s what’s coming and I happen to agree with it.
Oh no, you can't let scientific facts get in your way.


Title: RE: 1500 pep output max
Post by: W5HRO on January 20, 2016, 03:14:19 PM
Jokers? You mean to physicists and engineers.

I will rephrase that, ignoramuses

Quote
The thermocouple meter measures RMS current, not power. That current indication, using Ohm's law, is used to calculate power; that power is the average or mean power.

Duh... didn't I say thermocouple ammeters

Quote
What are you trying to argue anyway, "RMS power" vs average/mean power, or PEP vs average/mean power? Two different topics.

Both...

Quote
Read the specs from Bird on the APR-16 average power meter (see the link in a previous post), and they will tell you that the instrument is incapable of measuring the average power of a modulated AM signal.

I have and have used one. The price is around 1K. So far those are the best thing on the market made available to hams, but they are still not 100% accurate, but they are 50 x better than the majority of those junky PEP meters SSB operators use that do pretty much do nothing else except lie to them.

Quote
What "the industry" and marketers say does not make it a scientific reality.

The electronics industry, RF and AF both.

Quote
Oh no, you can't let scientific facts get in your way.

And you cannot let backwards thinking set in their ways old Internet trolls stand in the way of progress.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 20, 2016, 04:08:41 PM
Quote from: HRO
The other guys post was just badly worded and what he was trying to say just didn’t come out right at first so it made everything confusing especially when he threw the word harmonics in there with it. It even confused me at first because it sounded like he didn’t really know anything.

I feel the same way when I read your posts. ;D


Quote from: HRO
The issue that I have and have always had is that is only referes to one cycle and one cycle is what is also used to calculate Average/Mean power based on a set of predetermined values from a perfect symmetrical sinewave. Well, in the real world under normal operating conditions with voice communications for example that perfect symmetrical sinewave does not exist so most meters used to measure it (not PEP meters) basically preform a quick and dirty avg/mean measurement that is not 100% accurate.

Quote from: K1ZJH
...peak power would seem to be based the  maixma of the largest AC RF crest for a single RF cycle, not the modulating waveform.

That was my understanding as well.

Let's take for example an AM transmitter system at 1.8 Mhz, with a good pi-net filter and low harmonic content at no modulation loaded into 50 ohms. If you examine the waveform across the load with a scope you will see repetitive voltage peaks spaced 0.56 useconds apart.

At 100 watts (average) power, with no modulation, the voltage across the load will be 70.7 volts rms, or 100V Peak. Mathematically, the Instantaneous Peak Power at that Peak voltage will be (Vpeak)^2/R = 200 Watts.

Now, keep zooming to the top of that peak. How long does that peak last, or what is the "duration or width" of that peak? The duration of that peak is very small to infinitely small.  So the Instantaneous Peak Power at the Peak Voltage is almost meaningless.

The RMS voltages in those IC's are mathematically integrated over time since instantaneous (Peak) values are almost too short to measure.

This is why these RMS and Peak-to-Average IC's use a modified (normalized) value of the RMS voltage in order to derive (calculate) the peak-to-average power ratios.

Now, modulate the waveform with audio and of course, the voltage amplitude of the modulated waveform increases. But, those 0.56 usecond repetitive sine waves are still there. Those Instantaneous peak voltages will simply increase to higher levels.

But again, those peak voltage points, at whatever voltage amplitude, have such a short duration that power cannot be accurately measured without throwing in an RMS calculation.



Title: RE: 1500 pep output max
Post by: QRP4U2 on January 20, 2016, 04:48:38 PM
Quote from: HRO
Quote
What "the industry" and marketers say does not make it a scientific reality.

The electronics industry, RF and AF both.

Incorrect again, El Brino. Not everyone in the microwave industry is calling them what the LT marketing department or the Audiophulz may be calling these devices.

The Linear Technology company makes great some stuff, and their LTSpice software is tops. But it sounds like the engineers need to educate some of their technicians and marketing people in order to keep those people from making incorrect declarations in public.

Quote from: HRO
Quote
Oh no, you can't let scientific facts get in your way.

And you cannot let backwards thinking set in their ways old Internet trolls stand in the way of progress.

Backwards thinking only comes from individuals whose education and attitude prevent them from going forward.

Since you have your own website, why not go there and argue your case with those other 5 members?


Title: RE: 1500 pep output max
Post by: K4KYV on January 20, 2016, 04:50:09 PM
Quote
Read the specs from Bird on the APR-16 average power meter...
...the majority of those junky PEP meters SSB operators use that do pretty much do nothing else except lie to them.
I'll have to agree with you on that one.

Quote
Quote
What "the industry" and marketers say does not make it a scientific reality.
The electronics industry, RF and AF both.

You mean the ones that tout $600 "high end" power cords for the stereo amplifier, claiming that the power cord makes an "astounding difference" in the sound coming out of the speaker? The ones that sell $1200 speaker cables, when plain old zip cord would not make a discernible difference? Of course, those expensive  cables don't sound any different from cheap one when first hooked up, because they have to be "broken in" with hours of use (unless you plunk down $500 for a "cable breaker-inner" that breaks in power cords and speaker cables in just a couple of hours.

http://www.eetimes.com/author.asp?section_id=1&doc_id=1284433

http://www.positive-feedback.com/Issue47/cablecooker.htm  

http://www.gcaudio.com/resources/howtos/powercords.html


Title: RE: 1500 pep output max
Post by: W5HRO on January 20, 2016, 05:12:55 PM
Incorrect again, El Brino. Not everyone in the microwave industry is calling them what the LT marketing department or the Audiophulz may be calling these devices.

And once again, El Ass Hole opinions are just like you name.

Quote
Backwards thinking only comes from individuals whose education and attitude prevent them from going forward.

But some individuals who have the education (or just think they do) let their big egos ruin their attitudes and they only feel like someone when putting down others.

Quote
Since you have your own website, why not go there and argue your case with those other 5 members?

What would be the point in that? The discussion is here. It's not much of a discussion, but nevertheless.


Title: RE: 1500 pep output max
Post by: KM3F on January 20, 2016, 05:29:23 PM
Would anyone care to comment on the QST article page 46 Feb 2016 issue.
Look at the left  hand column under Power handling capacity, and W/rms  reference by the author, where he references that term to thermal effects on various cables tested under a set of conditions..



Title: RE: 1500 pep output max
Post by: QRP4U2 on January 20, 2016, 05:59:50 PM
Quote from: HaRO
.. It's not much of a discussion, but nevertheless.

Which is why I suggested you go back to your website and do your name-calling and cursing there, which you seem to like to do.

I find this discussion very interesting, save for one, cursing, name-calling, troll.

HaRO, you have to realize that this website is not your website so you cannot bring your narcissistic and bullying attitude here without some pushback.


Title: RE: 1500 pep output max
Post by: W5HRO on January 20, 2016, 06:09:05 PM
HaRO, you have to realize that this website is not your website so you cannot bring your narcissistic and bullying attitude here without some pushback.

I don't mind the pushback at all, I just tell it like it is, so....


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 20, 2016, 08:50:43 PM
Would anyone care to comment on the QST article page 46 Feb 2016 issue.
Look at the left  hand column under Power handling capacity, and W/rms  reference by the author, where he references that term to thermal effects on various cables tested under a set of conditions..



I don't receive QST, but did this chart show a graph of Wattage per RMS voltage?

Any thermal effects have to be due to rms currents or voltages.

Any chance of scanning it in?

Thanks,

Phil - Ac0OB


Title: RE: 1500 pep output max
Post by: K4KYV on January 20, 2016, 11:11:10 PM
Would anyone care to comment on the QST article page 46 Feb 2016 issue.
Look at the left  hand column under Power handling capacity, and W/rms  reference by the author, where he references that term to thermal effects on various cables tested under a set of conditions..

He says that WRMS is "your power output in FM or RTTY modes". FM and RTTY are essentially a pure, steady sine wave carrier, shifted slightly in frequency/phase with modulation. This frequency shift modulation produces sidebands but unlike AM, has zero effect on the net power output. Therefore, the average (mean) and peak power are the same, so he is clearly referring to average power.  He doesn't include a footnote to define what WRMS is supposed to stand for; he could have intended this to mean "power derived from RMS voltage and current", but WAVG" (average power) would have been better. If he intended this to mean "RMS power", then like others we have referred to on this thread, he was wrong, since there is no such thing. Just because one writes an article in QST doesn't mean one is infallible.

http://www.eznec.com/Amateur/RMS_Power.pdf


Title: RE: 1500 pep output max
Post by: G3RZP on January 21, 2016, 01:23:38 AM
Do QST have articles peer reviewed before publication, in the same way as RSGB does?


Title: RE: 1500 pep output max
Post by: W5HRO on January 21, 2016, 11:39:41 AM
Do QST have articles peer reviewed before publication, in the same way as RSGB does?

It's too bad this board doesn't have an animated laughing emoticon.


Title: RE: 1500 pep output max
Post by: K4KYV on January 21, 2016, 11:48:28 AM
I e-mailed the following to the author of the QST article, and look forward to his reply:

Quote
I  read your article on coaxial cable in February QST. 

While I found the article interesting and informative, I wish to point out what appears to me to be an error in terminology.  On page 46, under the heading  "Power handling capability" you state : "The power is Wrms, which would equal your power output in FM or RTTY modes.  Since it is based on thermal effects..."  The output from a FM or RTTY transmitter would essentially be a pure, steady sine wave carrier,  shifted slightly in frequency/phase with modulation. This frequency shift modulation produces sidebands but unlike AM, has zero effect on the net power output. The average (mean) and peak power are the same, so you clearly referred here to average power, since average, or mean, power is what produces thermal effects.  Without a footnote to clearly define exactly what "Wrms" stands for, I have to assume you may have intended this to mean "RMS power". Perhaps you actually meant "average power as derived from RMS voltage and current", but "Wavg" (average power) would have been a better symbol.

There is no  such thing as "RMS power", even though the term is widely but erroneously used by audio enthusiasts.  RMS voltage times RMS current = average, or mean power.  Average voltage times average current renders a physically meaningless quantity. While the RMS value of any periodically varying function can be mathematically calculated, in the case of power, the result of this calculation likewise has no physical significance.  The following paper clearly explains, without delving into complex mathematical calculations, the reason why "RMS power" is a meaningless quantity.

http://www.eznec.com/Amateur/RMS_Power.pdf

Thank you for your attention in this matter.

73,

Donald Chester, k4kyv


Title: RE: 1500 pep output max
Post by: W5HRO on January 21, 2016, 12:53:42 PM
The admin here and on qrz.com both should create a special moderator group called "Terminology Moderators" and give them access to edit everyone’s posts when they use the wrong term along with the ability to issue warnings that say “Warning you have used the wrong term in your post” “Repeat violations will result in the loss of privileges.”

And some actually had the nerve to complain when the moderators of that other rinky dink AM board said something about the misuse of terms and/or spelling errors. It’s obvious now where that came from ::)


Title: RE: 1500 pep output max
Post by: AD5X on January 21, 2016, 01:42:02 PM
Do QST have articles peer reviewed before publication, in the same way as RSGB does?

It's too bad this board doesn't have an animated laughing emoticon.

Well, I don't know how the RSGB does it.  The ARRL has a Technical Review Committee of about a dozen folks that reviews all QST and QEX submittals.  Besides a "publish or reject" vote, the TRC members also make recommendations/suggestions/corrections that go back to the author of any accepted material.  After the author makes the corrections, a technical writer re-writes the article as necessary.  Then the author gets to check if once more prior to publication.  Of course, some errors still creep in as you can see in the "Feedback" paragraphs that are published in most issues.

Phil - AD5X


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 21, 2016, 02:39:19 PM


...And some actually had the nerve to complain when the moderators of that other rinky dink AM board said something about the misuse of terms and/or spelling errors. It’s obvious now where that came from ::)

Oh yea, heard about that one.

It's called, "amnorthsoutheastwestupdownamerica" or some such and its Emperor goes by, El Brino.    ;D

Quote
It's too bad this board doesn't have an animated laughing emoticon.


That's okay, we still laugh at your posts anyway!  :-[


Phil - AC0OB


Title: RE: 1500 pep output max
Post by: KM1H on January 21, 2016, 03:19:10 PM
Quote
It had absolutely nothing to do with that Don or the topic you mentioned. You just wanted a place to ventilate and that was all which is apparent by the topics you also start on qrz.com now-a-days. I would think after all these years you would quit finding ways to keep complaining about the exact same topics over and over again. It's actually a good thing you never did come back. Carl did and I had to run him back off because of the way he is. Phil is a different story though. He always felt like he had to compete with me for whatever reason just like here. It's always been about EGOs with you guys and that's been the whole problem from the very beginning. You guys do the same garbage on every board you go to.

Now if that was true why do I still keep getting annoying emails from you telling me a post I replied to a long time ago, 6-12 months, has received a reply?

You didnt kick me off and I just stopped connecting for the same reason as Don, your forum is useless since you cant shut up and have to reply to everything....and wrong more than you are right.
The only EGO on that board is yours, there isnt room for another.....and the same on QRZ and AMFone but cant be bothered to get involved with some over there by replying except by direct PM's. At least there is excellent technical stuff over there at times and run into many on the air.

Of course you WILL just HAVE TO reply to this for ego and damage control spin as always.



Title: RE: 1500 pep output max
Post by: K4KYV on January 21, 2016, 05:10:54 PM
The origin of the"RMS Power" nonsense
by Paul D Quillen, N4LCD.  See bio on QRZ.com, or his web page at http://www.n4lcd.com/

This is a classic example of bureaucrats, with good intentions but nevertheless ignorant of technical facts, making technical decisions.

Both RMS Power and RMS Watts are a fiction created by the Federal Trade Commission. In the mid-1970's the FTC decided that they would create a standard for power ratings for power amplifiers.  Their motivation was furniture store stereo consoles rated at 800 Watts that actually put out a few Watts...blatantly false advertising. Of course, everyone knew that the furniture store power ratings were a joke, but the FTC saw it as an opportunity to regulate. 

After 25 years, in 2000, the FTC finally got the RMS issue right, and  changed the standard to "continuous average power output, in watts, per channel", but apparently a lot of people in the audiophile community never got the message. 

http://www.n4lcd.com/RMS.pdf



Title: RE: 1500 pep output max
Post by: WB4JTR on January 22, 2016, 06:47:50 AM
I e-mailed the following to the author of the QST article, and look forward to his reply:

Quote
I  read your article on coaxial cable in February QST. 

While I found the article interesting and informative, I wish to point out what appears to me to be an error in terminology.  On page 46, under the heading  "Power handling capability" you state : "The power is Wrms, which would equal your power output in FM or RTTY modes.  Since it is based on thermal effects..."  The output from a FM or RTTY transmitter would essentially be a pure, steady sine wave carrier,  shifted slightly in frequency/phase with modulation. This frequency shift modulation produces sidebands but unlike AM, has zero effect on the net power output. The average (mean) and peak power are the same, so you clearly referred here to average power, since average, or mean, power is what produces thermal effects.  Without a footnote to clearly define exactly what "Wrms" stands for, I have to assume you may have intended this to mean "RMS power". Perhaps you actually meant "average power as derived from RMS voltage and current", but "Wavg" (average power) would have been a better symbol.

There is no  such thing as "RMS power", even though the term is widely but erroneously used by audio enthusiasts.  RMS voltage times RMS current = average, or mean power.  Average voltage times average current renders a physically meaningless quantity. While the RMS value of any periodically varying function can be mathematically calculated, in the case of power, the result of this calculation likewise has no physical significance.  The following paper clearly explains, without delving into complex mathematical calculations, the reason why "RMS power" is a meaningless quantity.

http://www.eznec.com/Amateur/RMS_Power.pdf

Thank you for your attention in this matter.

73,

Donald Chester, k4kyv


Hello comrads. 

In this case, Wavg has the same ambiguity as Wrms (or RMS power).  1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds.

Obviously, what this author means is continuous or sustained power at a given ambient temperature.  Maybe Wsus or Wcont would have been more descriptive.

Can I have my Terminology Police badge now?

"No soup for you.....Next!"


Title: RE: 1500 pep output max
Post by: K4KYV on January 22, 2016, 08:06:18 AM
In this case, Wavg has the same ambiguity as Wrms (or RMS power).  1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds.

Obviously, what this author means is continuous or sustained power at a given ambient temperature.  Maybe Wsus or Wcont would have been more descriptive.

"RMS power" is not merely ambiguous; it's erroneous, since it represents a quantity with no physical reality.  The FTC, who originally coined the phrase, eventually retracted the term from the original rule and replaced it with "sine wave continuous average power output"

"Wavg", as used in the QST article, would have been ambiguous without an additional qualifier, as in the word "continuous" in the FTC rule.  In the QST article, the writer indeed inserted a qualifier with the words "which would equal your power output in FM or RTTY modes".  Since FM and RTTY modes inherently produce a continuous sine wave carrier, there is nothing ambiguous about what he meant when he composed the article; the ambiguity was whether or not he suggested a scientifically incorrect entity in the description.  "Wrms" would have been unambiguous and perfectly credible had he coupled it with a footnote stating that "Wrms" means "average power, derived from RMS voltage or current". "Wavg", with no further footnote or explanation, would have been satisfactory, with the qualifier the writer included in the QST article.

Even when the correct meaning can be inferred from a text, the use of erroneous or imprecise language in a scientific or engineering treatise lessens its credibility, just as misspelt words and incorrect grammar lessen a job applicant's credibility in a CV or a résumé, and lessen a reporter's credibility in a news story.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 22, 2016, 11:40:18 AM
In this case, Wavg has the same ambiguity as Wrms (or RMS power).  1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds.

Obviously, what this author means is continuous or sustained power at a given ambient temperature.  Maybe Wsus or Wcont would have been more descriptive.

"RMS power" is not merely ambiguous; it's erroneous, since it represents a quantity with no physical reality.  The FTC, who originally coined the phrase, eventually retracted the term from the original rule and replaced it with "sine wave continuous average power output"

"Wavg", as used in the QST article, would have been ambiguous without an additional qualifier, as in the word "continuous" in the FTC rule.  In the QST article, the writer indeed inserted a qualifier with the words "which would equal your power output in FM or RTTY modes".  Since FM and RTTY modes inherently produce a continuous sine wave carrier, there is nothing ambiguous about what he meant when he composed the article; the ambiguity was whether or not he suggested a scientifically incorrect entity in the description.  "Wrms" would have been unambiguous and perfectly credible had he coupled it with a footnote stating that "Wrms" means "average power, derived from RMS voltage or current". "Wavg", with no further footnote or explanation, would have been satisfactory, with the qualifier the writer included in the QST article.

Even when the correct meaning can be inferred from a text, the use of erroneous or imprecise language in a scientific or engineering treatise lessens its credibility, just as misspelt words and incorrect grammar lessen a job applicant's credibility in a CV or a résumé, and lessen a reporter's credibility in a news story.

In other words it all depends on the context.  There are contexts in which Wavg, Wrms, Average power, and RMS power are appropriate.  In this present context Wsus or Wcont would be a better fit, even without further explanation for the context-challenged.

If you are a statistician discussing the standard deviation of power available from a PV installation in watts over a specified time period, after calculating the RMS value of the hourly (or daily, or even per second) deviation, you may well choose Wrms or RMS power as a term for your answer in watts.  It's not incorrect or "against terminology law".  It' s just a different context than you are used to.  And it's no different than using RMS volts, even though RMS voltage is not found in nature.  RMS is just a scalar factor applied to the voltage that DOES exist to accomplish a purpose in the context of heat-equivalence.  Maybe we should try to force everybody to use the term "RMS value of voltage" since RMS voltage just doesn't exist.



Title: RE: 1500 pep output max
Post by: QRP4U2 on January 22, 2016, 01:15:35 PM
 
Quote
Maybe we should try to force everybody to use the term "RMS value of voltage" since RMS voltage just doesn't exist.

How about we quit beating around the bush and simply use the expression, Average power =Irms* Vrms = Irms^2*R = Vrms^2/R.

By definition the rms value of an AC sine voltage is .707XPeak = 0.3535XPeak-to-Peak.

By definition the equivalent, physical, DC heating value for a resistor is Irms^2*R.

Quote
1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds.

How would do that?   ???


Title: RE: 1500 pep output max
Post by: N0GW on January 22, 2016, 02:01:32 PM
"1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds."

And it would be 100KW PEP.


Title: RE: 1500 pep output max
Post by: W5HRO on January 22, 2016, 02:11:39 PM
Now if that was true why do I still keep getting annoying emails from you telling me a post I replied to a long time ago, 6-12 months, has received a reply?

You should not be getting any emails your account was removed more than 12 months ago. Thank God...

RMS POWER FOREVER guys... ;)



Title: RE: 1500 pep output max
Post by: K4KYV on January 22, 2016, 02:12:11 PM
There are contexts in which Wavg, Wrms, Average power, and RMS power are appropriate.  In this present context Wsus or Wcont would be a better fit, even without further explanation for the context-challenged.

If you are a statistician discussing the standard deviation of power available from a PV installation in watts over a specified time period, after calculating the RMS value of the hourly (or daily, or even per second) deviation, you may well choose Wrms or RMS power as a term for your answer in watts.  It's not incorrect or "against terminology law".  It' s just a different context than you are used to.  And it's no different than using RMS volts, even though RMS voltage is not found in nature.  RMS is just a scalar factor applied to the voltage that DOES exist to accomplish a purpose in the context of heat-equivalence.

You can go through the gymnastics of mathematical calculations for the RMS value of any periodically varying quantity that can be predicted or described in terms of a mathematical function, including voltage, current, power, temperature and oceanic tides.

RMS voltage and RMS current have a physical significance that is indeed found in nature, due to the inherent characteristics of a sine wave, just as the irrational number pi (3.14...) is inherently related to a circle. A fundamental a.c., sound or other wave frequency is by definition a sine wave.  Any deviation from the sine wave is evidence of the presence of harmonics.  As shown by the Fourier transform concept, any recurring waveform of any shape can be resolved into a sum of sine wave (or cosine wave) fundamental and (co)sine wave harmonics.  The (co)sine wave's characteristic is an occurrence in nature, just  like pi, e, and the other irrational mathematical operators. What we see displayed as a sine wave on an oscilloscope is identical to the projection of a constant rotary motion onto a two-dimensional surface (paper or oscilloscope screen), as the Y axis moves along the X axis at a constant rate.  That's why pi appears so often in formulae describing alternating current, frequency and resonance. This is also in evidence when fractions of wavelengths are often expressed in degrees; for example, a quarter-wave antenna may be described as a 90-degree antenna. The RMS value of current or voltage of an a.c. sine wave is always 0.707 times the peak value. Look it up an any engineering text to find the mathematical proof.

OTOH, the RMS value of power, while it can be calculated mathematically, cannot be shown to have any physical significance beyond mathematical gymnastics, particularly in terms of thermal equivalence.  

The only "context" of RMS power versus RMS voltage and current is the context of demonstrable physical reality. The realities of Santa Claus, the tooth fairy and Aladdin's magic lamp are likewise based whatever "contexts" you may be used to, or have ever been exposed to.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 22, 2016, 02:28:00 PM
There are contexts in which Wavg, Wrms, Average power, and RMS power are appropriate.  In this present context Wsus or Wcont would be a better fit, even without further explanation for the context-challenged.

If you are a statistician discussing the standard deviation of power available from a PV installation in watts over a specified time period, after calculating the RMS value of the hourly (or daily, or even per second) deviation, you may well choose Wrms or RMS power as a term for your answer in watts.  It's not incorrect or "against terminology law".  It' s just a different context than you are used to.  And it's no different than using RMS volts, even though RMS voltage is not found in nature.  RMS is just a scalar factor applied to the voltage that DOES exist to accomplish a purpose in the context of heat-equivalence.

You can go through the gymnastics of mathematical calculations for the RMS value of any periodically varying quantity that can be predicted or described in terms of a mathematical function, including voltage, current, power, temperature and oceanic tides.

RMS voltage and RMS current have a physical significance that is indeed found in nature, due to the inherent characteristics of a sine wave, just as the irrational number pi (3.14...) is inherently related to a circle. A fundamental a.c., sound or other wave frequency is by definition a sine wave.  Any deviation from the sine wave is evidence of the presence of harmonics.  As shown by the Fourier transform concept, any recurring waveform of any shape can be resolved into a sum of sine wave (or cosine wave) fundamental and (co)sine wave harmonics.  The (co)sine wave's characteristic is an occurrence in nature, just  like pi, e, and the other irrational mathematical operators. What we see displayed as a sine wave on an oscilloscope is identical to the projection of a constant rotary motion onto a two-dimensional surface (paper or oscilloscope screen), as the Y axis moves along the X axis at a constant rate.  That's why pi appears so often in formulae describing alternating current, frequency and resonance. This is also in evidence when fractions of wavelengths are often expressed in degrees; for example, a quarter-wave antenna may be described as a 90-degree antenna. The RMS value of current or voltage of an a.c. sine wave is always 0.707 times the peak value. Look it up an any engineering text to find the mathematical proof.

OTOH, the RMS value of power, while it can be calculated mathematically, cannot be shown to have any physical significance beyond mathematical gymnastics, particularly in terms of thermal equivalence.  

The only "context" of RMS power versus RMS voltage and current is the context of demonstrable physical reality. The realities of Santa Claus, the tooth fairy and Aladdin's magic lamp are likewise based whatever "contexts" you may be used to, or have ever been exposed to.

A good basic summary.  And mostly true.  Until you began denial of any context outside of thermal equivalence.  It clearly demonstrates a view of reality limited to a small corner of engineering.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 22, 2016, 02:34:50 PM
"1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds."

And it would be 100KW PEP.

Bingo!


Title: RE: 1500 pep output max
Post by: KK4YDR on January 22, 2016, 02:35:21 PM
13495 views......

Eating pop corn and drinking a coke..... lets see how insanely large this thread can get.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 22, 2016, 02:47:18 PM
Quote
Maybe we should try to force everybody to use the term "RMS value of voltage" since RMS voltage just doesn't exist.

How about we quit beating around the bush and simply use the expression, Average power =Irms* Vrms = Irms^2*R = Vrms^2/R.

By definition the rms value of an AC sine voltage is .707XPeak = 0.3535XPeak-to-Peak.

By definition the equivalent, physical, DC heating value for a resistor is Irms^2*R.

Quote
1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds.

How would do that?   ???

I think we can all agree with your presentation of the basic definitions of the RMS value of voltage and power averaged over one cycle (Well maybe not all of us).  Just don't refer to it as "RMS voltage" or even Vrms, in any context, or you will be incarcerated by the Terminology Police and informed RMS voltage does not exist in nature!  And then...
"No soup for you..."


Title: RE: 1500 pep output max
Post by: K4KYV on January 22, 2016, 04:17:10 PM
Quote
Maybe we should try to force everybody to use the term "RMS value of voltage" since RMS voltage just doesn't exist.
RMS voltage does exist.
RMS voltage and RMS current have measurable physical significance.  RMS power, RMS watts and the RMS value of wattage can be calculated as a number, but this would have no measurable or theoretical physical significance.

Quote
How about we quit beating around the bush and simply use the expression, Average power =Irms* Vrms = Irms^2*R = Vrms^2/R.

By definition the rms value of an AC sine voltage is .707XPeak = 0.3535XPeak-to-Peak.

By definition the equivalent, physical, DC heating value for a resistor is Irms^2*R.
That about sums it up.  "Mean" power would be close enough, too.

Quote
1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds.
Quote
How would do that?   ???

By taking the average output power, integrated over 100-second intervals. Since it would not be a continuous sine wave, average power over that period could not be calculated based on the peak or RMS value of the voltage or current, without taking into account the waveform of the envelope. Nor would that average value have any meaning over a period of less that 100 seconds. Here, we are  getting into two different perspectives, one cycle of the "envelope" waveform versus one cycle of a.c. during those one second intervals. That's where the confusion regarding "p.e.p." and "average power over one rf cycle at the crest of the modulation envelope" comes in. If hams have difficulty comprehending and agreeing on basic concepts like average and peak power/voltage/ current, RMS voltage/current and how these are all interelated, how can one expect the average Joe Bloe ham to understand and be able to explain what p.e.p. is, let alone how to accurately measure it, beyond mindlessly noting what his Hammy Hambone "wattmeter" reads when inserted into his coax feedline, working into a load of uncertain resistance and reactance? And to complicate things further, some ham (and commercial) radio installations don't have a sprig of coax between the final output stage of the transmitter and the radiating element of the antenna.

Quote
I think we can all agree with your presentation of the basic definitions of the RMS value of voltage and power averaged over one cycle (Well maybe not all of us).  Just don't refer to it as "RMS voltage" or even Vrms, in any context, or you will be incarcerated by the Terminology Police and informed RMS voltage does not exist in nature!  
No, you will be subject to arrest only when you start referring to "RMS power" or "RMS watts".  Ask the Federal Trade Commission.


Title: RE: 1500 pep output max
Post by: WB4JTR on January 22, 2016, 06:07:47 PM
Quote
Maybe we should try to force everybody to use the term "RMS value of voltage" since RMS voltage just doesn't exist.
RMS voltage does exist.
RMS voltage and RMS current have measurable physical significance.  RMS power, RMS watts and the RMS value of wattage can be calculated as a number, but this would have no measurable or theoretical physical significance.

Quote
How about we quit beating around the bush and simply use the expression, Average power =Irms* Vrms = Irms^2*R = Vrms^2/R.

By definition the rms value of an AC sine voltage is .707XPeak = 0.3535XPeak-to-Peak.

By definition the equivalent, physical, DC heating value for a resistor is Irms^2*R.
That about sums it up.  "Mean" power would be close enough, too.

Quote
1KWavg could easily be interpreted as 100KW for one second repeated every 100 seconds.
Quote
How would do that?   ???

By taking the average output power, integrated over 100-second intervals. Since it would not be a continuous sine wave, average power over that period could not be calculated based on the peak or RMS value of the voltage or current, without taking into account the waveform of the envelope. Nor would that average value have any meaning over a period of less that 100 seconds. Here, we are  getting into two different perspectives, one cycle of the "envelope" waveform versus one cycle of a.c. during those one second intervals. That's where the confusion regarding "p.e.p." and "average power over one rf cycle at the crest of the modulation envelope" comes in. If hams have difficulty comprehending and agreeing on basic concepts like average and peak power/voltage/ current, RMS voltage/current and how these are all interelated, how can one expect the average Joe Bloe ham to understand and be able to explain what p.e.p. is, let alone how to accurately measure it, beyond mindlessly noting what his Hammy Hambone "wattmeter" reads when inserted into his coax feedline, working into a load of uncertain resistance and reactance? And to complicate things further, some ham (and commercial) radio installations don't have a sprig of coax between the final output stage of the transmitter and the radiating element of the antenna.

Quote
I think we can all agree with your presentation of the basic definitions of the RMS value of voltage and power averaged over one cycle (Well maybe not all of us).  Just don't refer to it as "RMS voltage" or even Vrms, in any context, or you will be incarcerated by the Terminology Police and informed RMS voltage does not exist in nature!  
No, you will be subject to arrest only when you start referring to "RMS power" or "RMS watts".  Ask the Federal Trade Commission.

I see there are not only a certain amount of the contextually challenged but also at least one of the irony-challenged in this thread.  The RMS voltage argument was an obvious strawman designed to demonstrate the ridiculous obcession of the Terminology Police Force, allowing them to hoist up on their own petard.

They obviously didn't need my help to demonstrate that.

Chill..........or:
" No soup..."


Title: RE: 1500 pep output max
Post by: W5HRO on January 23, 2016, 08:22:41 AM
The RMS voltage argument was an obvious strawman designed to demonstrate the ridiculous obcession of the Terminology Police Force, allowing them to hoist up on their own petard.

I'll say it again; it's too bad this board doesn't have an animated laughing emoticon.

One of the guys in this thread once corrected me when I used the term AVC and he said it was AGC. Like there is a difference ::)

I still like to use many of the older terms like Mc instead of MHz, etc. But hey, it’s just like with all of the political correctness nonsense today. You say the wrong thing and some people tend to flip out and have a cow over it.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 23, 2016, 11:33:42 AM
Quote from: K4KYV
... If hams have difficulty comprehending and agreeing on basic concepts like average and peak power/voltage/ current, RMS voltage/current and how these are all interelated, how can one expect the average Joe Bloe ham to understand and be able to explain what p.e.p. is, let alone how to accurately measure it, beyond mindlessly noting what his Hammy Hambone "wattmeter" reads when inserted into his coax feedline, working into a load of uncertain resistance and reactance? And to complicate things further, some ham (and commercial) radio installations don't have a sprig of coax between the final output stage of the transmitter and the radiating element of the antenna.

I have often wondered if the FCC's PEP language wasn't stated the way it is in order to be either purposely or somewhat ambiguous.

I mean, I don't  keep a continuous oscilloscope probe across my feedline to my vertical, and I don't zoom in to the peaks each time to calculate instantaneous peak power. Besides, my envelope crests vary widely with different speech patterns, such as early morning speech verses late night speech.

So in my view, if I am on AM and I keep my carrier at the fantasy 375 Watts or below, I am pretty much guaranteed that my PEP power to the antenna feedpoint is less than the whimsical 4X375 Watts = 1500 Watts PEP, since I have feedline losses, ATU tuning component losses, ground losses etc.


Title: RE: 1500 pep output max
Post by: K4KYV on January 23, 2016, 11:34:11 AM

One of the guys in this thread once corrected me when I used the term AVC and he said it was AGC. Like there is a difference ::)

I still like to use many of the older terms like Mc instead of MHz, etc. But hey, it’s just like with all of the political correctness nonsense today. You say the wrong thing and some people tend to flip out and have a cow over it.

You're comparing apples to oranges.

Nothing wrong with using "automatic volume control" instead of "automatic gain control".  They are both valid descriptions of the same thing, and "AVC" dates back to the invention of the circuit.

"Hertz", along with its related multiples (kHz, MHz, etc), was first established by the International Electrotechnical Commission in 1930. The term can be seen occasionally from that date, in pre- and post-WWII radio publications and periodicals, mostly European but as I recall, at least once in a 1930s QST.  Decades later, in 1960, it was officially adopted by the General Conference on Weights and Measures to replace the term "cycles per second" and its related multiples. The term began to appear in popular use by the mid 60s. Nevertheless, "cycles per second" is still a valid term, accurately describing a physical phenomen, just as the term "coulombs per second" is still a valid substitute for "ampere", and "joules per second" for "watt".  I recall a question about the latter in my General Class exam in 1959.

OTOH, "RMS power" and "RMS watts" describes a mathematical operation that has been repeatedly confirmed by reputable sources (see previous links in this thread) to have no physical significance.  This is not merely an older term that has been replaced with a more recent trendy phrase that means the same thing.  It was originally coined, erroneously, when Federal Trade Commission bureaucrats, probably lawyers with limited technical knowledge and understanding, incorrectly assumed that if you measure RMS Voltage and current, the result from the I-squared x R and V-squared/R formulae for power would be "RMS watts". This was eventually retracted by the FTC in favour of valid terminology.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 23, 2016, 12:04:38 PM
Quote
One of the guys in this thread once corrected me when I used the term AVC and he said it was AGC.

Sometimes they do refer to the same thing, sometimes they refer to different circuit functions; it depends on the context.

AVC in audio literature refers to directly controlling audio levels somewhere in the audio chain.

In receivers and RF, AGC or AVC can refer to controlling the gain of RF amplification stages, which in turn affects audio levels.

I have actually seen different manufacturers refer to same function as AGC or AVC.

But this topic of AVC or AGC is mute since once again, it is a ploy to direct attention away from the fact that El Brino cannot admit he made inaccurate statements about Rms & Peak To Average Power Detectors, real-time analog computation devices that use modified rms detectors to determine near-instantaeous peak powers.  :o


Title: RE: 1500 pep output max
Post by: K7KBN on January 23, 2016, 12:52:47 PM
Quote
One of the guys in this thread once corrected me when I used the term AVC and he said it was AGC.

Sometimes they do refer to the same thing, sometimes they refer to different circuit functions; it depends on the context.

AVC in audio literature refers to directly controlling audio levels somewhere in the audio chain.

In receivers and RF, AGC or AVC can refer to controlling the gain of RF amplification stages, which in turn affects audio levels.

I have actually seen different manufacturers refer to same function as AGC or AVC.

But this topic of AVC or AGC is mute since once again, it is a ploy to direct attention away from the fact that El Brino cannot admit he made inaccurate statements about Rms & Peak To Average Power Detectors, real-time analog computation devices that use modified rms detectors to determine near-instantaeous peak powers.  :o

That's "moot", not "mute".


Title: RE: 1500 pep output max
Post by: W5HRO on January 23, 2016, 01:17:39 PM
See, told ya

AVC was the old original term used in receivers because it meant Automatic Volume Control by controlling the gain of the IF stage and that controlled the loudness coming from the speaker when strong signals were present. Then on down the road the industry started calling it AGC for Automatic Gain Control instead, but its still the same thing.


Title: RE: 1500 pep output max
Post by: N6PJB on January 23, 2016, 01:26:34 PM
I prey that this thread is muted.  ;D


Title: RE: 1500 pep output max
Post by: WB4JTR on January 23, 2016, 02:01:42 PM
I prey that this thread is muted.  ;D

:)


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 23, 2016, 02:30:18 PM
"...But this topic of AVC or AGC is mute..."


"Tongue-in-Cheek and a smidgeon of sarcasm it is," said Yoda.  ;D  :o


Title: RE: 1500 pep output max
Post by: KM1H on January 23, 2016, 06:02:16 PM
Quote
I see there are not only a certain amount of the contextually challenged but also at least one of the irony-challenged in this thread.  The RMS voltage argument was an obvious strawman designed to demonstrate the ridiculous obcession of the Terminology Police Force, allowing them to hoist up on their own petard.

They obviously didn't need my help to demonstrate that.

Chill..........or:
" No soup..."

It is a shame you have to resort to such garbage talk post after post when youre already on the cusp of being completely ridiculous when it comes to the actual subject.

Id say you came to Eham via trolling for "audiophool", "RMS power" or similar strictly to start an argument.

It is overdue for the moderator to end this farce.


Title: RE: 1500 pep output max
Post by: W5HRO on January 23, 2016, 06:16:20 PM
I prey that this thread is muted.  ;D

They should delete the whole thing  ;)


Title: RE: 1500 pep output max
Post by: WB4JTR on January 23, 2016, 07:09:17 PM
...Id say you came to Eham via trolling for "audiophool", "RMS power" or similar strictly to start an argument...

OK Carl.  Have it your way.

Once again:   Move on...


Title: RE: 1500 pep output max
Post by: WB4JTR on January 23, 2016, 07:19:50 PM
I prey that this thread is muted.  ;D

They should delete the whole thing  ;)

At least all the parts that don't relate directly to the PEP power regulation.  Most this preferred terminology stuff relating to RMS calculation of power is pretty much irrelevant.


Title: RE: 1500 pep output max
Post by: K4KYV on January 24, 2016, 09:18:46 AM
I prey that this thread is muted.  ;D

They should delete the whole thing  ;)

At least all the parts that don't relate directly to the PEP power regulation.  Most this preferred terminology stuff relating to RMS calculation of power is pretty much irrelevant.

Methods of power calculation is indeed relevant, including average power as calculated from RMS voltage/current.  Probably a majority of the 700,000-plus in the FCC data base don't have a clue, or at least lack a complete understanding of what PEP is,  let alone how to accurately measure it.  Technical issues brought up here need to be more widely discussed throughout the amateur radio community.

What made this thread a farce is the individual(s) making complete asses and fools of themselves, refusing to accept, then continuing to argue against, irrevocable technical principles backed up by authoritative sources. Check-mated by facts, the offender(s) then resorted to goofy name-calling and personal attacks. Reminds me of some of the garbage heard in recent political debates.

No need to lock or delete anything; no-one is holding a gun to anyone's head and forcing them to click on the link to this thread.


Title: RE: 1500 pep output max
Post by: W5HRO on January 24, 2016, 10:21:51 AM
No need to lock or delete anything; no-one is holding a gun to anyone's head and forcing them to click on the link to this thread.

Don,

The whole point is that if someone calls the calculations used to measure what you consider Avg/mean power RF Power it is insignificant and irrelevant.

Avg/Mean power is calculated by predetermined values based on a perfect sinewave. In the real world it is not fully accurate. If modern technology has found a way to better measure average power by sampling the crest of the RF envelope over a give time period and people want to call it RMS Power then that is a good thing, regardless of what you or anyone else on here thinks.

I fully agree with you about the FCC not having a clue and that was fully apparent back in the 1990’s when that FCC agent knocked on my door after receiving numerous complaints from my neighbors about telephone interference when I operated on 75-meters. He brought in his Bird digital wattmeter and we hooked it up to the output of my Desk KW and when I loaded everything up on AM into the antenna the meter read around 750 watts. He said, “Well, you can run more power than that.” I then proceeded to ask him about the confusion regarding AM and PEP limits and he had sort of a puzzled look on his face. He either just didn’t have a clue or he just didn’t want to tell me, but there was no way he was going to be able to measure PEP.

Anyway, that’s what this topic should be about and not the same old grip, “There is no such thing as RMS Power.” Nobody cares…


Title: RE: 1500 pep output max
Post by: K4KYV on January 24, 2016, 12:22:19 PM
One of the reasons the FCC gave for PEP was that they claimed it was too difficult to define and measure what "average power" is, even though average power, integrated over a voice syllable in the case of phone, or the character of the shortest duration (for example, a "dit" on CW), is what determines the effective loudness of a signal and hence its interference potential.

Actually, DC input is the easily measurable power standard most relevant to average power output. There was no APM-16 in 1983, and the Bird specs say that even the APM only measures average carrier power on AM.  The problem with PEP is that it increased legal power for some modes and decreased it for others.  This might have even been a conflict of interest with certain FCC personnel. Johnny Johnston who was apparently one who had been pushing for PEP several years in previous proposals before the that proceeding was even launched, stated at a Dayton FCC forum that his mode of choice was RTTY.  Under the changes, RTTY got a 3 dB increase in legal power, while AM allegedly got a 3 dB decrease.

In the NPRM the FCC said that it was their intention to "improve" the method for measuring power, not change the actual power amateurs used, but then they proceeded to substantially change the legal power for numerous modes.  The FCC went on to argue that anything other than their one-size-fits-all approach would have complicated the wording of the rules too greatly.

Canada used to have the same 1 kw input standard as the US.  After the changes in the US,  Canada adopted its own output-power standard, but managed to avoid a significant change in the actual power limit for any of the various modes, and the wording of their rules remains pretty simple. Evidently, Canadians are smarter than United States-ese:

Standards for the Operation of Radio Stations in the Amateur Radio Service RIC-2

10.2 Amateur Radio Operator Certificate with Basic and Advanced Qualifications

The holder of an Amateur Radio Operator Certificate with Basic and Advanced Qualifications is limited
to a maximum transmitting power of:

(a) where expressed as direct-current input power, 1,000 W to the anode or collector circuit of the
transmitter stage that supplies radio frequency energy to the antenna; or
(b) where expressed as radio frequency output power measured across an impedance-matched load,
(i) 2,250 W peak envelope power for transmitters that produce any type of single sideband
emission, or
(ii) 750 W carrier power for transmitters that produce any other type of emission


As you can see, Canadians now enjoy greater power privileges than do US  hams for both AM and SSB phone, and their power limit for AM remained essentially unchanged.  Under the old DC input rule, US hams could run unlimited peak power, as long as the DC input never exceeded 1,000 watts, using DC instruments (per published FCC notice) with a time constant not to exceed 0.25 seconds for full-scale deflection. Since the peak-to-average ratio of the voice waveform varies with individuals, someone with a high peak-to-average ratio in his voice might run considerably more than 1500 watts PEP,  while keeping the DC input, and thus average power, at a lower value.  The bottom  line: the US power limit for SSB was also reduced.  This only encourages heavy speech processing that results in raspy, distorted signals, and in many cases, its associated splatter. Another, often overlooked consequence of this change, was the curtailment of experimentation with pulse emissions on frequencies where this mode is legal.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 24, 2016, 02:11:32 PM
Quote from: El Brino, AKA, HaROH
If modern technology has found a way to better measure average power by sampling the crest of the RF envelope over a give time period and people want to call it RMS Power then that is a good thing, regardless of what you or anyone else on here thinks.

And you still don't know how these power detection devices function, even though it has been explained to you at least twice.

This argument of yours is based on a logical fallacy from the Latin, argumentum ad ignorantiam or, "Arguing from Ignorance."

Calling it RMS power is still incorrect and you have to be totally ignorant of the inner workings of these devices in order to continue to argue for RMS power.


Quote from: K4KYV
...As you can see, Canadians now enjoy greater power privileges than do US  hams for both AM and SSB phone, and their power limit for AM remained essentially unchanged.  Under the old DC input rule, US hams could run unlimited peak power, as long as the DC input never exceeded 1,000 watts, using DC instruments (per published FCC notice) with a time constant not to exceed 0.25 seconds for full-scale deflection. Since the peak-to-average ratio of the voice waveform varies with individuals, someone with a high peak-to-average ratio in his voice might run considerably more than 1500 watts PEP,  while keeping the DC input, and thus average power, at a lower value.  The bottom  line: the US power limit for SSB was also reduced.  This only encourages heavy speech processing that results in raspy, distorted signals, and in many cases, its associated splatter. Another, often overlooked consequence of this change, was the curtailment of experimentation with pulse emissions on frequencies where this mode is legal.

I often wonder if the people of the caliber of ignorance as HRO weren't advising the FCC with regard to this ambiguous 1500 Watt PEP rule.

Quote from: El Brino, AKA HaROH
They should delete the whole thing


BTW, I say keep the thread going and if the pro-RMS Power crowd still doesn't understand the physics and mathematics of power calculation, they can simply return to their caves and crayons.

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: KM1H on January 24, 2016, 02:28:56 PM
I couldnt agree more Phil.



Title: RE: 1500 pep output max
Post by: AA6CJ on January 24, 2016, 04:54:28 PM
My motive for starting this post was to suggest that pep was really limiting the output power when comparing it to cw or rtty.  Boy I had no idea that there would be so much discussion stemming from trying to figure out an alternative to ssb's limited factor using pep because of the peaky transients that occur.

I've read two articles on CESSB.  Frankly that seems much more likely to help me reach my goal...more average power from Ssb.  If I recall the claim is 2.65db gain with little distortion.

Regards,
Fred


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 24, 2016, 05:27:28 PM
My motive for starting this post was to suggest that pep was really limiting the output power when comparing it to cw or rtty.  Boy I had no idea that there would be so much discussion stemming from trying to figure out an alternative to ssb's limited factor using pep because of the peaky transients that occur.

I've read two articles on CESSB.  Frankly that seems much more likely to help me reach my goal...more average power from Ssb.  If I recall the claim is 2.65db gain with little distortion.

Regards,
Fred

Hi Fred,

I assume you are referring to this method of increasing SSB envelope power?

http://www.arrl.org/files/file/QEX_Next_Issue/2014/Nov-Dec_2014/Hershberger_QEX_11_14.pdf

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: K4KYV on January 24, 2016, 08:59:28 PM
My motive for starting this post was to suggest that pep was really limiting the output power when comparing it to cw or rtty.  Boy I had no idea that there would be so much discussion stemming from trying to figure out an alternative to ssb's limited factor using pep because of the peaky transients that occur.

I have about a 4-inch thick file of paper copies in my filing cabinet related to the power change docket, including many of the submitted comments (this was in the pre-ECFS days, when it was very inconvenient and difficult for anyone outside of DC to browse through the  comment file), as well as official and unofficial releases from the FCC including the original NPRM, R&O, petitions for reconsideration, and the final Order. I still hope to some day be able to scan and post the whole thing on a web site. That way, everyone could see for themselves how it was ill-conceived, self-contradictory, and fraudulently railroaded through by the Private Radio Bureau who lied and dodged issues, to be rubber-stamped by the non-technical lawyer-type FCC commissioners.


Title: RE: 1500 pep output max
Post by: AA6CJ on January 25, 2016, 05:39:01 AM

Hi Fred,

I assume you are referring to this method of increasing SSB envelope power?

http://www.arrl.org/files/file/QEX_Next_Issue/2014/Nov-Dec_2014/Hershberger_QEX_11_14.pdf

Phil - AC0OB
Yes


Title: RE: 1500 pep output max
Post by: AA6CJ on January 25, 2016, 05:49:48 AM
My motive for starting this post was to suggest that pep was really limiting the output power when comparing it to cw or rtty.  Boy I had no idea that there would be so much discussion stemming from trying to figure out an alternative to ssb's limited factor using pep because of the peaky transients that occur.

I have about a 4-inch thick file of paper copies in my filing cabinet related to the power change docket, including many of the submitted comments (this was in the pre-ECFS days, when it was very inconvenient and difficult for anyone outside of DC to browse through the  comment file), as well as official and unofficial releases from the FCC including the original NPRM, R&O, petitions for reconsideration, and the final Order. I still hope to some day be able to scan and post the whole thing on a web site. That way, everyone could see for themselves how it was ill-conceived, self-contradictory, and fraudulently railroaded through by the Private Radio Bureau who lied and dodged issues, to be rubber-stamped by the non-technical lawyer-type FCC commissioners.

Sounds political to the extreme!  Any Idea why they railroaded as they did?


Title: RE: 1500 pep output max
Post by: W5HRO on January 25, 2016, 06:04:33 AM
[And you still don't know how these power detection devices function, even though it has been explained to you at least twice.

I fully understand how they work and was involved with them upon release. Yet someone like you who was/is so far removed wants to keep carrying on about it.

This argument of yours is based on a logical fallacy from the Latin, argumentum ad ignorantiam or, "Arguing from Ignorance."

The only person who is ignorant is you.

Calling it RMS power is still incorrect

RMS POWER FOREVER


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 25, 2016, 08:48:41 AM
Quote from: El Brino, AKA HaRO
I fully understand how they work and was involved with them upon release. Yet someone like you who was/is so far removed wants to keep carrying on about it.


Quote from: QRP4U2
This argument of yours is based on a logical fallacy from the Latin, argumentum ad ignorantiam or, "Arguing from Ignorance."

You may have been involved with them but apparently you don't understand the mathematics behind them, nor do you understand their actual functioning, or you would not be Arguing from Ignorance.

I have designed both Digital and Analog IC's for Military applications and for commercial systems, so I do not have to debate from ignorance.

Again, I point the interested reader to Hittite Microwave Devices for a more informative disclosure on the devices under discussion.

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 25, 2016, 09:22:59 AM
My motive for starting this post was to suggest that pep was really limiting the output power when comparing it to cw or rtty.  Boy I had no idea that there would be so much discussion stemming from trying to figure out an alternative to ssb's limited factor using pep because of the peaky transients that occur.

I have about a 4-inch thick file of paper copies in my filing cabinet related to the power change docket, including many of the submitted comments (this was in the pre-ECFS days, when it was very inconvenient and difficult for anyone outside of DC to browse through the  comment file), as well as official and unofficial releases from the FCC including the original NPRM, R&O, petitions for reconsideration, and the final Order. I still hope to some day be able to scan and post the whole thing on a web site. That way, everyone could see for themselves how it was ill-conceived, self-contradictory, and fraudulently railroaded through by the Private Radio Bureau who lied and dodged issues, to be rubber-stamped by the non-technical lawyer-type FCC commissioners.

Sounds political to the extreme!  Any Idea why they railroaded as they did?

My theory is there was an agenda and bias against certain operating modes such as AM and RTTY, etc.

I.E, some felt that the SSB phone mode was not getting a fair shake in the power realm, so an attempt was made to Peanut Butter power output emissions.

However, what the legal and technically ignorant numb-nuts at the FCC did was to enact an artificial power restriction that was both ambiguous and unnecessarily complicated, and screwed up sensible power levels for phone modes, including SSB.

My opinion is, if there is any petition to be made to the FCC, it should be a petition to follow the Canadian rules as Don mentioned earlier in this thread, and without involving the ARRL.

The Canadian rules are simple, clear, and unambiguous. :D

I would glady sign that petition.

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: W5HRO on January 25, 2016, 11:35:23 AM
I have designed both Digital and Analog IC's for Military applications and for commercial systems, so I do not have to debate from ignorance.

And yet you still act like an asshole who is so far removed from our devices that anything you say is completely meaningless.


Title: RE: 1500 pep output max
Post by: W1BR on January 25, 2016, 11:37:47 AM
I am going to ask a silly question... then I am going to go hide on QRZ.com for a few weeks.  ;D

Assuming a RF cycle is a sinusoidal waveform, wouldn't anything called "RMS Power" be based on the peak voltage, times .707, to find the RMS value for the RF voltage for that AC cycle?  Power would be derived using other known entities via the power or Ohms Law formulas.  

 



Title: RE: 1500 pep output max
Post by: K4KYV on January 25, 2016, 12:27:16 PM
I am going to ask a silly question... then I am going to go hide on QRZ.com for a few weeks.  ;D
This thread is getting more and more to resemble some of the ones that show up on QRZ.com.
Quote
Assuming a RF cycle is a sinusoidal waveform, wouldn't anything called "RMS Power" be based on the peak voltage, times .707, to find the RMS value for the RF voltage for that AC cycle?  Power would be derived using other known entities via the power or Ohms Law formulas.
"RMS"  voltage or current means taking the formula for a sinusoidal waveform and calculating the RMS value.  For mathematical reasons, that turns out to be 0.707 times the peak value (of voltage or current).

But POWER is a square-law function.  Voltage squared divided by the resistance, or current squared times the  resistance.  The instantaneous power level does not vary sinusoidally with time, as do the instantaneous voltage and current, but  with the SQUARE of the sinusoidal variations.  This variation can be described with a mathematical equation, but not the same one that describes sinusoidal variations of voltage and current.

"RMS power" would mean taking the equation or formula describing the variation of instantaneous power with time, and mathematically deriving the RMS value of that function (see the links cited in previous posts). Yes, you could mathematically calculate the RMS value of the periodically varying instantaneous power, but it would not describe the equivalent thermal effect of DC power dissipated in a resistor, and it would NOT be 0.707 times peak power.  In fact, it would be just a number that would not describe any physical phenomenon at all; it would be nothing beyond practice in mathematical manipulation and calculation, maybe a good exercise for students to complete in algebra class.

Taking the RMS voltage and multiplying it by the RMS current yields the average or mean value of power, which would describe the thermal effect of the power being dissipated into a resistor.  The RMS value, calculated as described in the preceding paragraph would be a different number that would not be the same as Vrms x Irms, or Vrms-squared/R or Irms-squared x R.

The misnomer "RMS power" was coined by non-technical Federal Trade Commission bureaucrats and lawyers who, when writing rules intended to curtail widespread deceptive advertisement of consumer electronics audio amplifiers, merely ASSUMED without further verifying the facts, that power derived from RMS voltage and RMS current would be something called "RMS power". Rules were written requiring stereo amplifiers to be rated in terms of "RMS watts".  It took a quarter-century for the FTC to retract this error, but by the time they did, the meaningless term "RMS power" appears to have become firmly implanted in the minds of certain audio enthusiasts, who never got the message when FTC changed the wording of the rules to correctly reflect physics. Now, they insist on sticking with the term, come  hell or high water, scientific and engineering facts be damned.  Just consider the source.




Title: RE: 1500 pep output max
Post by: W5HRO on January 25, 2016, 12:28:31 PM
Assuming a RF cycle is a sinusoidal waveform, wouldn't anything called "RMS Power" be based on the peak voltage, times .707, to find the RMS value for the RF voltage for that AC cycle?

Vrms = peak x .7071 to be exact

Or

Vrms = peak-to-peak x .35355

Or

Vrms = Average x 1.1107

then I am going to go hide on QRZ.com for a few weeks.  ;D

That wont help, these guys are on there too  ;D


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 25, 2016, 12:31:55 PM
I have designed both Digital and Analog IC's for Military applications and for commercial systems, so I do not have to debate from ignorance.

Quote from:  El Brino, AKA HaRO
And yet you still act like an asshole who is so far removed from our devices that anything you say is completely meaningless.

Some people are so far removed from reality and scientific facts they have to resort to name calling and act like children when they can't discuss topics as knowledgeable adults.

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: W5HRO on January 25, 2016, 01:14:20 PM
Despite what AH keeps saying the LT and LTC 5500 series RMS Power detectors that were first referenced here and not by me are in fact designed for specific applications. I referenced that one because it had already be mentioned because of it’s use of the term RMS Power on the datasheet.

Instead of using conventional log-antilog RMS-to-DC detectors you can just use an RMS-to-DC converter to sample the crest factors instead. This issue with those though is they tend to have very narrow bandwidths, but they could be used to create decent RMS RF power measurements from the true RMS voltages.

The technology is there if you put all of the separate pieces together to better measure the average power of a signal or modulated signal.


Title: RE: 1500 pep output max
Post by: W5HRO on January 25, 2016, 02:49:02 PM
Oh, and one last final thing, the below link is to a paper of just several papers that started floating around several years ago.

http://eprints.eemcs.utwente.nl/8519/01/Aa._F.H.J._vander_MSc2006_An_RF_%28R%29_MS_Power_Detector_in_Standard_CMOS.pdf

Look at the second paragraph in paragraph 2.3 for example...

"Usually it is sufficient to measure the RMS voltage to calculate the power, because most communication systems have constant load impedance (usually 50 Ω). So many practical power measurement circuits measure only the RMS voltage, but this is not the right way to measure the radiated power of an antenna, because the impedance of an antenna can change by surrounding objects, which distort the antenna pattern. This leads to impedance mismatch and causes reflections. When this happens, the measured voltage contains incident and reflected voltages and indicates the radiated power not correctly. Thus for this study, only the incident voltage has to be provided."

That's why I originally jumped into this topic when the ITU spec was being quoted. Also notice the use of the term RF Power like in the paper’s title “An RF (R)MS Power Detector in Standard CMOS.




Title: RE: 1500 pep output max
Post by: QRP4U2 on January 25, 2016, 02:54:29 PM
In spite of W5HRO attempting to obfuscate the issue by throwing out terms he doesn't really understand, here is another attempt to explain these incorrectly described, and so-called RMS power detector devices.

There are basically two "cores" in these devices. Core is a term used here to denote a major computational cell, a cell of circuitry that computes something in real time, or in this case, the computation of an analog value.

There are two major cores in these devices: One is an envelope detector core and the other is an RMS detector core. These devices also contain ancillary circuitry for signal conditioning, etc.

The  envelope detector core extracts the envelope information of the modulated RF signal for signals with large bandwidths. This extracted envelope information is independent of the average power and the crest factor of the RF signal. The envelope detector core then provides, as an output, a linear representation of the instantaneous envelope (input) waveform.

The RMS detector core thus provides a linear-in-dB output of the average RF power.

With these outputs, one can get a snapshot of the peak power, average power, the peak-to-average power ratio, and RF waveshape.


It is incorrectly called an "RMS power detector" by some errant tech writers, but in reality this device is simply a power detector that uses envelope detection in combination with average RF power detection (executed by an RMS detector), to determine the peak power, average power, and peak-to-average power ratios.

Maybe W5HRO can explain why the logarithmic term from the RMS voltage detector is missing from the final output voltage expression of these devices that makes it the ghostly, "RMS Power Detector."

Phil - AC0B




Title: RE: 1500 pep output max
Post by: W5HRO on January 25, 2016, 03:43:04 PM
In spite of W5HRO attempting to obfuscate the issue by throwing out terms he doesn't really understand, here is another attempt to explain these incorrectly, and so-called RMS power detector devices.

There are basically two "cores" in these devices. Core is a term used here to denote a major computational cell, a cell of circuitry that computes something in real time, or in this case, the computation of an analog value.

There two major cores in these devices: One is an envelope detector core and the other is an RMS detector core. These devices also contain ancillary circuitry for signal conditioning, etc.

The  envelope detector core extracts the envelope information of the modulated RF signal for signals with large modulated bandwidths. This extracted envelope information is independent of the average power and the crest factor of the RF signal. The envelope detector core then provides, as an output, a linear representation of the instantaneous envelope (input) waveform.

The RMS detector core thus provides a linear-in-dB output of the average RF power.

With these outputs, one can get a snapshot of the peak power, average power, the peak-to-average power ratio, and RF waveshape.


It is incorrectly called an "RMS power detector" by some errant tech writers, but in reality this device is simply a power detector that uses envelope detection in combination with average RF power detection (executed by an RMS detector), to determine the peak power, average power, peak-to-average power ratios.

Maybe W5HRO can explain why the logarithmic term from the RMS voltage detector is missing from the final output voltage expression of these devices that makes it a ghostly, "RMS Power Detector."

Phil - AC0B

Unfortunately AH I do understand, but unlike you I’m not going to get on a freaking ham board and post stuff such as device technology and the physics behind it when it is way over everyone’s head trying to make myself look good by attempting to make me look bad which is the exact same thing you always tried to do on my board. I was involved in and reading about this stuff back when it first started.

Anyway, I’ve said my peace so if you don’t like it then too bad….

You just continue on however trying to make yourself look good and like I said on qrz recently “nice try”, but I am no longer biting.

Have fun AH


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 25, 2016, 03:55:18 PM
Quote from: EL-Brino, W5HRO
...Unfortunately AH I do understand, but unlike you I’m not going to get on a freaking ham board like you and post stuff such as device technology and the physics behind it when it is way over everyone’s head..

Have fun AH


The explanation was primarily for your benefit since apparently it is way over your head because you were the one promoting the misunderstanding of power detection and their devices, as you can neither explain its functioning NOR its mathematics.

Quote from: QRP4U2
Some people are so far removed from reality and scientific facts they have to resort to name calling and act like children when they can't discuss topics as knowledgeable adults.

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: K4KYV on January 26, 2016, 10:28:56 AM
My theory is there was an agenda and bias against certain operating modes such as AM and RTTY, etc.

Phil - AC0OB

AM, yes, RTTY no.  Johnny Johnston and others working at the FCC at the time had clearly and consistently displayed hostility towards AM phone for at least a decade prior to the release of the power standard proposal.  Johnston joined the FCC around 1973, and the proposed rule was released in 1983. Right after Johnston came on board with the FCC, the original regulation-by-bandwidth proposal, Docket 20777 appeared, which would have prohibited the use of double-sideband AM, narrow-band FM and all other wide-band modes of greater bandwidth than SSB on all amateur frequencies below 28.5 MHz.  Fast-scan TV would have been eliminated from the 440 MHz band, where this mode was most widely used. The AM and FSTV communities jumped onto this immediately with a letter-writing campaign in those pre-internet days, and successfully organised enough opposition within the amateur community to generate comments to the FCC that caused the proposal to be rejected. There was likewise substantial opposition from members of the CW community who opposed the re-legalisation of tone-modulated CW, one of the unintended consequences of the bandwidth proposal.

Following the demise of the Docket 20777 bandwidth proposal (similar in many ways to the now-defunct ARRL regulation-by-bandwidth petition), the FCC entered into what is sometimes called the "docket-a-month era", with a long series of ill-conceived, poorly thought-out rulemaking proposals that would radically changed amateur radio in one way or another, usually to the detriment of the service/hobby.  A recurring theme in several of these proposals was some minor but substantive change that would have "just happened" to adversely affect AM phone privileges. The only one that eventually passed was the power limit change, fraudulently railroaded through by the Private Radio Bureau despite the expression of overwhelming opposition in the public comments received, and rubber-stamped by the non-technical, lawyer-type FCC commissioners.

RTTY, one of Johnston's self-proclaimed modes of preference at his own amateur station, benefited from the power change, with a two-fold increase in power.


Title: RE: 1500 pep output max
Post by: K6UJ on January 26, 2016, 11:56:38 AM
I have designed both Digital and Analog IC's for Military applications and for commercial systems, so I do not have to debate from ignorance.

Quote from:  El Brino, AKA HaRO
And yet you still act like an asshole who is so far removed from our devices that anything you say is completely meaningless.

Some people are so far removed from reality and scientific facts they have to resort to name calling and act like children when they can't discuss topics as knowledgeable adults.

Phil - AC0OB



Phil,
I have been following this thread.  Your posts are right on.
Dont let W5HRO get to you.
I look forward to his posts.  They are a source of entertainment.   :D

Bob
K6UJ


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 26, 2016, 01:41:14 PM
Quote from: K4KYV
AM, yes, RTTY no.  Johnny Johnston and others working at the FCC at the time had clearly and consistently displayed hostility towards AM phone for at least a decade prior to the release of the power standard proposal.  Johnston joined the FCC around 1973, and the proposed rule was released in 1983. Right after Johnston came on board with the FCC, the original regulation-by-bandwidth proposal, Docket 20777 appeared, which would have prohibited the use of double-sideband AM, narrow-band FM and all other wide-band modes of greater bandwidth than SSB on all amateur frequencies below 28.5 MHz....

Thanks Don for the clarification and the history of the "behind-the-scenes" shenanigans of the Johnny Johnston gang.

It was about '73 when I left Ham Radio temporarily to go back to school and to raise a family and somehow my Eico 720 got lost in a move.

Phil - AC0OB  


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 26, 2016, 01:54:46 PM
Quote from: K6UJ

Phil,
I have been following this thread.  Your posts are right on.
Dont let W5HRO get to you.
I look forward to his posts.  They are a source of entertainment.   :D

Bob
K6UJ

Thanks Bob.

I don't think I have ever seen a person get so personal, disrespectful, and just state outright falsehoods about other respected members on here and on other sites.

Sometimes you just have to treat people like children when they act like children.

There are too many nice and knowledgeable people on here to worry about one malcontent.

cheers :D

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: K4KYV on January 26, 2016, 02:12:55 PM
I have been following this thread.  Your posts are right on.
Dont let W5HRO get to you.
I look forward to his posts.  They are a source of entertainment.   :D

Bob
K6UJ

And a distraction from the topic at hand.  Look at how many posts were wasted arguing with him over well-understood electrical principles and a bogus issue that was settled a decade and half ago.  OTOH, with nearly 17,000 views, these exchanges might have shed some light for someone out there who had been totally confused over this business of average, RMS and peak voltage and current, average power, instantaneous peak power and peak envelope power.  But the name-calling, personal attacks and insults were uncalled for.


Title: RE: 1500 pep output max
Post by: AA6CJ on January 26, 2016, 06:09:05 PM
My opinion is, if there is any petition to be made to the FCC, it should be a petition to follow the Canadian rules as Don mentioned earlier in this thread, and without involving the ARRL.

The Canadian rules are simple, clear, and unambiguous. :D

I would glady sign that petition.

Phil - AC0OB

Phil, What Don says makes sense to me, and would bring parity.  In lieu of a regulation change, I'm entrigued by cessb and I've been thinking about buying a flex which comes with that standard.
Fred


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 26, 2016, 07:54:13 PM
My opinion is, if there is any petition to be made to the FCC, it should be a petition to follow the Canadian rules as Don mentioned earlier in this thread, and without involving the ARRL.

The Canadian rules are simple, clear, and unambiguous. :D

I would glady sign that petition.

Phil - AC0OB

Phil, What Don says makes sense to me, and would bring parity.  In lieu of a regulation change, I'm entrigued by cessb and I've been thinking about buying a flex which comes with that standard.
Fred

Most SDR's have incorporated Hershberger's CESSB system in software but I would not pay for an external box to only get maybe a realistic 2.0 dB increase in loudness.

My recommendation to SSB'ers is to use a quality mike, 3 to 6dB of compression and for everyone's sanity, never use an equalizer.

I have heard so many SSB'ers of late using W2IHY or equivalent equalizers and splattering over 7 kHz in the sideband.

SSB was never designed to be an extremely loud, Hi-Fidelity medium of communications. It's advantages were in less equivalent power to transmit, less sideband fade, less occupied spectrum, and greater signal to noise ratio.

Phil


Title: RE: 1500 pep output max
Post by: AA6CJ on January 27, 2016, 03:41:44 AM
Definitely agree with internal cessb vs external based on the articles I read.  I've been tuning into Heil's Hamnation talks about audio as well.  My HP strategy is to use low exciter drive power into the best tube amp I can get.  That plus a good mic and perhaps cessb internal eventually will do most of the trick.  I want a clean signal most of all!


Title: RE: 1500 pep output max
Post by: N4RSS on January 27, 2016, 06:52:38 AM



I'd be interested to hear how the use of an outboard box like W2IHY has anything to do with bandwidth.

Silly me, I thought that if one maintained judicious ALC action, regardless of what's input into the mike jack, splatter should be a non-issue.

Let's not let personal preferences cloud the science


Title: RE: 1500 pep output max
Post by: K4KYV on January 27, 2016, 09:13:09 AM
I'd be interested to hear how the use of an outboard box like W2IHY has anything to do with bandwidth.

Silly me, I thought that if one maintained judicious ALC action, regardless of what's input into the mike jack, splatter should be a non-issue.

ALC helps, but it's not a silver bullet nor substitute for effective speech processing. There will typically be over-shoot; those who turn the mic jack wide open and trigger ALC every syllable will still splatter. 

According to Collins Radio Company AMATEUR SERVICE INFORMATION LETTER (Feb 15, 1960), "What's Watt with SSB?",

Quote
...Measurement of thousands of voices have revealed the following peak to average power ratio of the human voice:

Bell Telephone 15 db
Signal Corps 13.8 db

By using some sort of compression, such as ALC, this peak to average ratio can be reduced to about 10 db.  This is an  average figure and can vary widely from voice to voice.

Assuming the above figures, with unprocessed speech, a SSB amplifier peaking 1500 watts output will deliver only about 150 watts average power to the antenna without splatter.



Title: RE: 1500 pep output max
Post by: QRP4U2 on January 27, 2016, 09:44:06 AM



I'd be interested to hear how the use of an outboard box like W2IHY has anything to do with bandwidth.

Silly me, I thought that if one maintained judicious ALC action, regardless of what's input into the mike jack, splatter should be a non-issue.

Let's not let personal preferences cloud the science


There are two primary considerations here: Input Audio Amplitude and the Audio Frequency spectrum.

We know that SSB is a form of AM modulation.

The amount of Audio Amplitude (magnitude of audio voltage) affects PEP.

The span of audio frequencies (audio spectrum) that are input to the mic connector affect occupied bandwidth. The higher the audio frequencies that get to the mic connector from out of the equalizer, the larger the bandwidth that is occupied.

Quote from: W2IHY 8-band equalizer specs
8 bands of equalization independently adjustable +/- 16dB
50, 100, 200, 400, 800, 1600, 2400, 3200 Hz

Let's assume you boost the high frequencies with the W2IHY equalizer controls, say the 2400 and the 3200 band controls.

You are boosting or increasing the high frequency content of your audio and thus increasing your occupied bandwith. And you cannot assume your radio's filtering system can filter out or decrease all of those high frequency components.

In addition, each audio equalizer's band has it's own bandwidth. In the case of the 3200 band, that bandwidth may go from a low of 2kHz to a high of 7 kHz or more.

This is of course assuming your microphone and speech articulation produces frequencies from 50 Hz to at least 7.5 kHz.

PHIL


Title: RE: 1500 pep output max
Post by: K4KYV on January 27, 2016, 11:38:12 AM
You are boosting or increasing the high frequency content of your audio and thus increasing your occupied bandwith. And you cannot assume your radio's audio input filter can filter out or decrease all of those high frequency components.
PHIL 

In a misguided attempt to transmit "hi-fi" SSB, some operators have been known to insert audio "equalisers" between the microphone and a stock radio, attempting to brute-force a frequency response beyond the bandwidth of the sideband filter.  This will not work, and only produces a distorted signal and may introduce splatter.

Those who have been successful at this accomplishment replaced the stock filter with something with a wider bandwidth, and in some cases extensively modified or replaced the stock balanced modulator and speech amplifier circuitry, or most likely nowadays, are simply taking advantage of software defined radio (SDR) technology already built into the radio.


Title: RE: 1500 pep output max
Post by: AA6CJ on January 28, 2016, 07:29:42 AM
The bandwidth is still limited by the TX filter that you use.  Collins was 2.1kHz, and I opted for the 2.7kHz filter for my k3s.  Bob Heil K9EID point out it all starts with understanding the fletcher munson curve, and if you want to punch through you need articulation which occurs in the 2-3 kHz range.

I would love to see the Collins report, and some Power Spectral Density charts on human voice.  I could use that with what Bob's teaching to ensure I reduce the lower frequency components of the signal that may be maxing be causing the peak in PEP but providing little in articulation.  In other words, I would like to get enough scientific data to control how I can maximize use of the frequencies within the constraints of the TX filter.

Hope that makes some sense.
73,
Fred, AA6CJ


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 28, 2016, 08:26:28 AM
The bandwidth is still limited by the TX filter that you use.  Collins was 2.1kHz, and I opted for the 2.7kHz filter for my k3s.  Bob Heil K9EID point out it all starts with understanding the fletcher munson curve, and if you want to punch through you need articulation which occurs in the 2-3 kHz range.

I would love to see the Collins report, and some Power Spectral Density charts on human voice.  I could use that with what Bob's teaching to ensure I reduce the lower frequency components of the signal that may be maxing be causing the peak in PEP but providing little in articulation.  In other words, I would like to get enough scientific data to control how I can maximize use of the frequencies within the constraints of the TX filter.

Hope that makes some sense.
73,
Fred, AA6CJ

Your original question Fred had to do with the amplitude factor, that is of attempting to get the largest SSB envelope possible.

Now we are into the realm of psychoacoustics and recording curves.

Back to the filtering system for a moment. Any filter has a skirt. Some skirts are sharp (almost straight)  but realistically, most have a certain amount of roll-off, or attenuation per dB, and little oscillations near the "break" points. Boosted high frequency content from an equalizer may still get get through and cause higher occupied bandwidths, and with over compressed high audio levels, cause distortion resulting in splattering.

If the radio has active filtering instead of mechanical or crystal filters, those can easily be overloaded causing splattering and high occupied bandwidths.

Phil


Title: RE: 1500 pep output max
Post by: W6RZ on January 28, 2016, 09:13:37 AM
I would love to see the Collins report, and some Power Spectral Density charts on human voice.  I could use that with what Bob's teaching to ensure I reduce the lower frequency components of the signal that may be maxing be causing the peak in PEP but providing little in articulation.  In other words, I would like to get enough scientific data to control how I can maximize use of the frequencies within the constraints of the TX filter.

Pretty easy to test with GNU Radio. Here's a waterfall of unprocessed speech with a 100 to 2800 Hz filter on both the transmitter and receiver. You can see that most of the power is at low frequencies (using upper sideband so there's no spectral inversion).

(http://www.w6rz.net/ssb100-2800Hz.png)

Here's some "hi-fi" SSB at 100 to 6000 Hz.

(http://www.w6rz.net/ssb100-6000Hz.png)

Here are the audio files.

Original audio input.

http://www.w6rz.net/ssbaudio.wav

100 to 2800 Hz SSB audio.

http://www.w6rz.net/ssb100-2800Hz.wav

100 to 6000 Hz SSB audio

http://www.w6rz.net/ssb100-6000Hz.wav

Fast AGC on SSB clips.


Title: RE: 1500 pep output max
Post by: W6RZ on January 28, 2016, 09:21:19 AM
BTW, I have a working partial implementation of CESSB that I'll post about soon.


Title: RE: 1500 pep output max
Post by: AA6CJ on January 28, 2016, 10:50:25 AM
Very cool W6Rz!

I know Phil your right.  I started the post because I realized how little power was actually being generated by ssb.  Frankly it shocked me when comparing Cw Rtty to ssb.  So it occurred to me that there had to be a better way to put the modes at parity.  I really like Don's posting on Canadian rules.  I'd sign it as well.

But admittedly I have other practical concerns to methods of getting the most out is whAt we have.  So I brought it into the thread because some of the guys contributing really have good stuff to share.  As a big gun/contester wannabe I want to get the most out of what I have without resorting to making things worse with splatter and imd.

Have a great day all & 73, Fred AA6CJ


Title: RE: 1500 pep output max
Post by: KM1H on January 28, 2016, 05:30:46 PM
Phil, several modify their rigs to TX thru the AM filter which gives them a 6kHz BW when the carrier oscillator is set properly and then modify the audio chain.

And as mentioned by Don many SDR's can do this with a few keystrokes.

Quote
The bandwidth is still limited by the TX filter that you use.  Collins was 2.1kHz, and I opted for the 2.7kHz filter for my k3s.  Bob Heil K9EID point out it all starts with understanding the fletcher munson curve, and if you want to punch through you need articulation which occurs in the 2-3 kHz range.

Fred, the all important sibilants are in the 3300-4000Hz range, right where the D-104 placed their peak back in the 30's. While this is good for natural sounding SSB with the male voice it isnt a pileup buster or a contesters space shuttle sounding audio.

I often use a TS-950SD on AM by setting the DSP audio BW with its switches and use a D-104 with a FET impedance transformer. On SSB I revert to an overhauled CE-100V boatanchor with a few simple audio mods and another D-104 for ragchewing. Once I get a SDR I can eliminate a few hundred pounds on the benches.
The D-104M6B does well as a hand held and the price is very low compared to the competition
http://radioproshop.com/microphones/astaticd104m6mic.htm

Carl


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 28, 2016, 06:05:46 PM
Quote from: FRED
As a big gun/contester wannabe I want to get the most out of what I have without resorting to making things worse with splatter and imd.

I am not a contester myself, but that is a worthwhile goal. You are a conscientious Ham.


Quote from: KM1H
Phil, several modify their rigs to TX thru the AM filter which gives them a 6kHz BW when the carrier oscillator is set properly and then modify the audio chain.

And as mentioned by Don many SDR's can do this with a few keystrokes.

I have heard many good SDR transmitters on both AM and SSB.

At RockwellCollins (and other companies) I helped to define many SDR architectures. They needed to not only be mode agile (FM, SSB, and mostly AM), they also had to be frequency and power output agile.

The main point I was trying to make to Roger N4RSS (post #246), is that outboard devices such as the W2IHY equalizer, if misused, could result in very wide bandwidths and splatter that play havoc with ongoing QSO's up and down the band.

Quote from: N4RSS
I'd be interested to hear how the use of an outboard box like W2IHY has anything to do with bandwidth.

Silly me, I thought that if one maintained judicious ALC action, regardless of what's input into the mike jack, splatter should be a non-issue.

Let's not let personal preferences cloud the science

Phil


Title: RE: 1500 pep output max
Post by: W1BR on January 28, 2016, 08:26:58 PM
If PEP power is defined by the peak voltage of the highest crest for an AC RF cycle, it would seem to be meaningless for all practical purposes...  unless I am very confused :) And I do confuse very easily.

 Of what practical worth is PEAK power, and how does it relate to heat energy--which should be the real definition of power?  Does this mean that the 2300 mc pulse transmitters described back in the sixties are now illegal, regardless of very short peak pulse RF levels, which equate to minuscule averaged power?

It seems the FCC has opened a Pandora's Box which few us understand.  Peak Power seems to be more and more meaningless, at least from I am seeing in this discussion.

Pete

 


Title: RE: 1500 pep output max
Post by: G3RZP on January 28, 2016, 11:59:00 PM
PEP  for SSB is well defined and has been the standard for more years than most of us have been alive - and even before the FCC existed! It is probably the only method to use when the transmitter in question is running ISB, with several MCVFT channels on one sideband and speech on the other. It is also a useful concept when modulations such as OFDM are used, because it accurately represents the transmitter power output requirements for various codings.


Title: RE: 1500 pep output max
Post by: W3RSW on January 29, 2016, 05:07:18 AM
Eimac / Varian has a very nice chapter, Section 4 I believe, in "Care and Feeding of Power Grid Tubes" that helps to understand PEP and its application to multi-channel signals.
http://www.cpii.com/library.cfm/9

This thread is so long it may have already been referenced. I've come in late.  ;D


Title: RE: 1500 pep output max
Post by: K4KYV on January 29, 2016, 10:18:44 AM
Eimac / Varian has a very nice chapter, Section 4 I believe, in "Care and Feeding of Power Grid Tubes" that helps to understand PEP and its application to multi-channel signals.
http://www.cpii.com/library.cfm/9

This thread is so long it may have already been referenced. I've come in late.  ;D

What about ARRL, when they simulcast W1AW on multiple bands, each transmitter running SSB at the full so-called "legal limit"?  Wouldn't the net PEP exceed 1500 watts?

I wonder if they even do that any more.  I still hear them on CW, but haven't heard a W1AW phone bulletin in several years.  


Title: RE: 1500 pep output max
Post by: W6RZ on January 29, 2016, 11:32:45 AM
Here are the results from my SDR CESSB implementation. This is a partial implementation, just the first stage of the W9GR algorithm. Here's the GNU Radio flow graph. It's a DSB modulator and filter SSB transmitter with a custom block (Magnitude Clipper) that I developed. All the other blocks are standard GNU Radio blocks.

I implemented the clipping block a little differently than W9GR, but it has the same functionality. Here's the algorithm:

1) Convert an IQ sample pair to magnitude and phase.
2) If the magnitude is greater than the clipping level, set the magnitude to the clipping level.
3) Re-create the IQ sample pair with the possibly clipped magnitude and original phase.

The advantage of this method is that it can be completely vectorized with x86 SIMD instructions.

(http://www.w6rz.net/cessbflow.png)

Unprocessed SSB envelope power.

(http://www.w6rz.net/ssb1.png)

Zoom in on the first 1/2 second.

(http://www.w6rz.net/ssb1zoom.png)

Clipped SSB envelope power.

(http://www.w6rz.net/ssb2.png)

Zoom in on the first 1/2 second.

(http://www.w6rz.net/ssb2zoom.png)

This waveform can be transmitted, but it will splatter. Here's what it looks like.

(http://www.w6rz.net/ssbclipped.png)

Clipped and filtered envelope power.

(http://www.w6rz.net/ssb3.png)

Zoom in on the first 1/2 second.

(http://www.w6rz.net/ssb3zoom.png)

Signal is nice and clean again.

(http://www.w6rz.net/ssbprocessed.png)

To try to get an idea of how much the peak to average power has increased, I've taken out the silence between syllables in the test audio clip.

The unprocessed average power is about 150 watts.

(http://www.w6rz.net/ssb4.png)

The processed average power is about 400 watts. A healthy 4.2 dB increase.

(http://www.w6rz.net/ssb5.png)

Here are the audio files. The first one is unprocessed SSB. AGC is set to medium for all clips.

http://www.w6rz.net/ssb-unprocessed.wav

Processed SSB.

http://www.w6rz.net/ssb-processed.wav

These next two clips are with more attenuation between TX and RX. This is trying to simulate weak signal conditions. Unprocessed SSB.

http://www.w6rz.net/ssb-unprocessed-low.wav

Processed SSB.

http://www.w6rz.net/ssb-processed-low.wav

Here's the audio test clip with the silence between syllables removed.

http://www.w6rz.net/ssbaudiopapr.wav


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 29, 2016, 12:49:03 PM
Quote from: W6RZ
...Here are the results from my SDR CESSB implementation. This is a partial implementation, just the first stage of the W9GR algorithm. Here's the GNU Radio flow graph. It's a DSB modulator and filter SSB transmitter with a custom block (Magnitude Clipper) that I developed. All the other blocks are standard GNU Radio blocks.

I implemented the clipping block a little differently than W9GR, but it has the same functionality. Here's the algorithm:

1) Convert an IQ sample pair to magnitude and phase.
2) If the magnitude is greater than the clipping level, set the magnitude to the clipping level.
3) Re-create the IQ sample pair with the possibly clipped magnitude and original phase.

The advantage of this method is that it can be completely vectorized with x86 SIMD instructions...

For me, I could not discern much of a difference in the unprocessed and unprocessed audio in terms of loudness. The only thing I could detect is that the unprocessed file had clearer articulation than the processed file.

Just a suggestion for your simulation:

You might want to explain some of the terminology used for the general audience.

Phil


Title: RE: 1500 pep output max
Post by: W6RZ on January 29, 2016, 01:14:14 PM
For me, I could not discern much of a difference in the unprocessed and unprocessed audio in terms of loudness. The only thing I could detect is that the unprocessed file had clearer articulation than the processed file.

The first two clips are well into the receiver AGC, so it's going to be difficult to discern loudness. Those clips were more to show that the processed audio sounds pretty good.

The second two clips were an attempt to show loudness. Here's another set of clips where the unprocessed SSB is at the esp level.

http://www.w6rz.net/ssb-unprocessed-esp.wav

http://www.w6rz.net/ssb-processed-esp.wav


Title: RE: 1500 pep output max
Post by: W6RZ on January 29, 2016, 01:45:49 PM
Trying to explain how IQ processing works is a little difficult in 25 words or less.  :) Here's a link for those that want to explore more.

http://whiteboard.ping.se/SDR/IQ

Hopefully, the SSB power graphs are fairly easy for folks to follow.

BTW, the audio clips are not a simulation. They are from two hardware SDR's connected back to back with coax and a 30 dB attenuator. It's actually easier to do it that way than try to simulate a noise floor.


Title: RE: 1500 pep output max
Post by: QRP4U2 on January 29, 2016, 01:47:24 PM
Quote from: K1ZJH
If PEP power is defined by the peak voltage of the highest crest for an AC RF cycle, it would seem to be meaningless for all practical purposes...  unless I am very confused Smiley And I do confuse very easily.

It indeed can be measured accurately with the proper detector circuits such as the IC's I discussed, but not with slow thermal or diode envelope detectors that have long thermal or electrical time constants, respectively.

However, you can determine it with a calibrated storage scope.

Here is another try at the math (forget the two-tone tests for the moment that the manf. have to make during testing).

1) Let's say you have a "T" connector connected to your 50 ohm non-reactive dummy load and a storage scope with a probe monitoring the load.

2) You input a constant, maxiumum level voice recording into your SSB rig. You measure a maximum voltage somewhere over the snapshot's time period. At some point in the snapshot, you zoom in to the waveform and observe a maximum of 200 Volts Peak-to-Peak across the load.

3) PEP = V^2/R = (200V P-P/2 X 0.707)^2 / 50 = (100V X 0.707)^2 / 50 = 5000/50 =
100 W PEP power.

Now, 200V Peak-to-Peak voltage is the same voltage you would see with a high amplitude sine wave (or any audio wave of any shape) inputted to your SSB rig and the PEP would still be 100 Watts PEP.

But here is the catch: In normal voice situations, this peak envelope power rarely occurs. In fact, with normal unprocessed voice, the Peak Envelope Power may only be 25-33 Watts PEP.

Quote from: W6RZ
BTW, the audio clips are not a simulation. They are from two hardware SDR's connected back to back with coax and a 30 dB attenuator. It's actually easier to do it that way than try to simulate a noise floor.

Thanks for the clarification.

Phil






 


Title: RE: 1500 pep output max
Post by: N0GW on January 30, 2016, 10:41:14 AM
"But here is the catch: In normal voice situations, this peak envelope power rarely occurs. In fact, with normal unprocessed voice, the Peak Envelope Power may only be 25-33 Watts PEP."

After 18 pages of this silliness, this sentence?

Nope, 100 watts PEP voice typically has 25-33 Watts Average Power.  I hope the sentence above was a typo.

Gary - N0GW
 


Title: RE: 1500 pep output max
Post by: AA6CJ on February 03, 2016, 07:48:57 PM
Hi all,
On Ssb that's a whole lot less average power out than other modes.  Has anyone tried petitioning the fcc to makke it average power out?
Fred, aa6cj

I edited this slightly to remove RMS.

Phil and others have well discussed how little average power is present - 25-33% without compression.  And that's spread across 200-2.8khz give or take of audio modulation.  Cw on the other hand has 1500 PEP watts at a single tone making it 1500 average watts.  The difference is 6db between Ssb and cw.  With cessb, really cool by the way, we close that difference by 2.65db ( I if I remember correctly.)

Now that the technology of rf sampling is coming available, I can foresee soon the ability to move from PEP to a metering that accurately measures the average power of the entire signal From 200 to 2.8kHz or so.  Cw will continue to have the advantage in s/n since all that power is being concentrated in a very narrow tone.  Fortunate for me I like cw!

I don't know if anything else can be said, but thanks all for contributing.  I had no idea ther'd be such response and interest.
73,
Fred, AA6CJ


Title: RE: 1500 pep output max
Post by: K4KYV on February 08, 2016, 05:59:51 PM
Cw will continue to have the advantage in s/n since all that power is being concentrated in a very narrow tone.  Fortunate for me I like cw!

I don't know if anything else can be said, but thanks all for contributing.  I had no idea ther'd be such response and interest.

One more thing to be added to the summary. Under the old DC input rule, the average power output consistently related to DC power input, by a factor representing the efficiency of the final stage.  All modes, regardless of peak-to-average ratio, were on a roughly equal playing field as far as average/mean output power was concerned.

Under the P.E.P. nonsense, certain phone modes (SSB as well as AM) suffered a substantial loss of power privilege, while CW, RTTY and FM gained 3 dB of legal power.  Turns out, by his own admission, the mode of choice of the now-retired chief of the Private Radio Bureau at that time (the bureau within the FCC that made the regulatory decisions for amateur radio) was RTTY. He basically gave himself 3 dB more legal power at the expense of users of other modes.  Conflict of interest?


Title: RE: 1500 pep output max
Post by: W1BR on February 08, 2016, 08:49:59 PM
And, what about hams who were using pulsed communications on the microwave bands?  The difference between pulse power and average power would be extreme.


Title: RE: 1500 pep output max
Post by: KK4YDR on February 08, 2016, 09:47:09 PM
This thread ought to be a sticky... so much information in this thread.

You could write a small book with some of this information


Title: RE: 1500 pep output max
Post by: K4KYV on February 09, 2016, 08:49:37 AM
And, what about hams who were using pulsed communications on the microwave bands?  The difference between pulse power and average power would be extreme.

It probably didn't affect a large number of on-the-air hams, but that facet of experimentation was essentially shut down.


Title: RE: 1500 pep output max
Post by: W1BR on February 09, 2016, 09:35:37 AM
And, what about hams who were using pulsed communications on the microwave bands?  The difference between pulse power and average power would be extreme.

It probably didn't affect a large number of on-the-air hams, but that facet of experimentation was essentially shut down.

Agreed.  I remember starting to build a 2300 mc pulse station back in the mid 60's based on ARRL material. I doubt many hams are doing pulse modulation these days.  It is too bad that these new regs were so badly thought out.

Pete


Title: RE: 1500 pep output max
Post by: YL3GND on February 14, 2016, 11:39:22 AM
"Putting RMS vs. peak power into perspective....

A continuous tone on SSB with a PEP of 1500 watts will provide an RMS output of 750 watts, which is "3 db"  "less", so it would take 3 KW PEP to achieve 1500 watts RMS with a single tone..

Brian K6BRN"


Sorry Brian but You are wrong about that..! A continuous tone on SSB with a PEP of 1500W is the same amount of RMS power = 1500W RMS !!!

Egmont


Title: RE: 1500 pep output max
Post by: W1BR on February 14, 2016, 01:41:34 PM
"Putting RMS vs. peak power into perspective....

A continuous tone on SSB with a PEP of 1500 watts will provide an RMS output of 750 watts, which is "3 db"  "less", so it would take 3 KW PEP to achieve 1500 watts RMS with a single tone..

Brian K6BRN"


Sorry Brian but You are wrong about that..! A continuous tone on SSB with a PEP of 1500W is the same amount of RMS power = 1500W RMS !!!

Egmont

So, by your definition, we'd use .707 times the peak sinusoidal AC voltage value shown on a scope to determine true power, regardless of mode--in order to determine power using Ohms law or the power formulas?   This assumes that the flywheel effect will produce a nearly pure sinusoidal waveform over each RF cycle in a Class B or C amplifier with reasonable PA tank Q???

This aspect of PEP or average power has never been clearly determined in any of the preceding posts.

Pete


Title: RE: 1500 pep output max
Post by: G3RZP on February 14, 2016, 03:25:07 PM
'Average power' requires a determination of the limits of the integral of power and time.


Title: RE: 1500 pep output max
Post by: K6AER on February 14, 2016, 06:24:40 PM
My God is this thread still going on? I have been out of country for 5 weeks and I connect believe RMS power is still being discussed. In the RF world Peak power is all that matters.


Title: RE: 1500 pep output max
Post by: K6BRN on February 14, 2016, 07:25:05 PM

Egmont (YL3GND):

You're right!  I transposed Peak Power with Peak Envelope Power (PEP), which is defined as:

"Peak Envelope Power (PEP) is defined as the average power supplied to the antenna transmission line by a
transmitter during one radio frequency cycle at the crest of the modulation envelope

taken under normal operating conditions.”

So a pure sinusoid whose envelope amplitude does not vary will have a PEP power equal to its Average power.

Thank you for the correction!  (Ooops!)

Brian K6BRN



Title: RE: 1500 pep output max
Post by: K6UJ on February 15, 2016, 10:01:25 AM
My God is this thread still going on? I have been out of country for 5 weeks and I connect believe RMS power is still being discussed. I the RF world Peak power is all that matters.


Mike,
I think we are going for the longest thread award  ;D ;D ;D ;D

Bob
K6UJ


Title: RE: 1500 pep output max
Post by: QRP4U2 on February 15, 2016, 01:31:40 PM
Quote
This aspect of PEP or average power has never been clearly determined in any of the preceding posts.

Pete

Sorry, that's not true as it has been explained and demonstrated correctly ad naseum.

The only thing that seems to survive is a misinterpretation, misconstruction, misreading, misapprehension, misconception, wrong idea, or a false impression of the issue.  :D

Phil - AC0OB


Title: RE: 1500 pep output max
Post by: AA6CJ on February 15, 2016, 04:21:37 PM
'Average power' requires a determination of the limits of the integral of power and time.

I think I agree.  The hard part is deciding the time interval to use to calculate the integral of power and to caclulate the average.  Instead of integrating a function of a human voice which is essentially impossible, one could sum the power during the time interval by sampling the power at a sufficiently high enough rate to approximate an integral function.  I believe the sample rate of the lp-100 wattmeter is 40khz when it calculates the peak to average ratio, for example. 


Title: RE: 1500 pep output max
Post by: W3RSW on February 16, 2016, 05:19:47 AM
Yes, already mentioned in a variety of expressions, dump the energy regardless of waveform into a calorimeter for a period of time sufficient to encompass most real speaking from whispers to expletives.  ;D

The true heat produced and measured will be a decent representation of the average power.


Title: RE: 1500 pep output max
Post by: AA6CJ on February 16, 2016, 04:47:51 PM
Two issues leap to mind: 1) time interval over which to average, and 2) average power at each time interval would change.  So how would you write the reg? 

"The average power during a transmission shall not exceed 1500 watts."  Probably not any worse than PEP not exceeding 1500 watts because whether you hit that maximum is hit or miss during any transmission. 

Maybe I'm not getting something....   Could you flesh out how heat could me used to monitor average power?


Title: RE: 1500 pep output max
Post by: W6RZ on February 17, 2016, 05:06:13 PM
"The average power during a transmission shall not exceed 1500 watts."

For some digital modes, that would be a fairly large PEP. Here's an example for wideband OFDM (which is known for high peak to average power ratio).

$ ./papr /media/re/ssd/dvbt2np.cfile
Peak magnitude = 0.941762
average power = 0.041590, peak power = 0.886917 @ 3041576360

Maximum PAPR = 13.288914
percentage above 0 dB = 36.80672888
percentage above 1 dB = 28.41393729
percentage above 2 dB = 20.50877964
percentage above 3 dB = 13.59744934
percentage above 4 dB = 8.10721626
percentage above 5 dB = 4.22612259
percentage above 6 dB = 1.85867800
percentage above 7 dB = 0.66065442
percentage above 8 dB = 0.17945542
percentage above 9 dB = 0.03479794
percentage above 10 dB = 0.00435299
percentage above 11 dB = 0.00031778
percentage above 12 dB = 0.00001202
percentage above 13 dB = 0.00000013

peak real positive = 0.909538, peak imaginary positive = 0.885237
peak real negative = -0.884373, peak imaginary negative = -0.861705

peak real positive @ 18908212192, peak imaginary positive @ 30649730873
peak real negative @ 3041576360, peak imaginary negative @ 30034821609

At 1500 watts average, the PEP will be over 6000 watts for approximately 1.8 percent of the time. There will be a very occasional peak at over 30 kW (the run time for this example was 11 minutes).

Do you really want 30 kW PEP amplifiers to be legal for amateur radio use?

The PAPR calculator is available here:

https://github.com/drmpeg/dtv-utils/blob/master/papr.c


Title: RE: 1500 pep output max
Post by: G3RZP on February 18, 2016, 04:48:11 AM
It's because of those high peaks that COFDM (Coded OFDM) was thought up. That specifically gets rid of those relatively few codes that need very high PEP.


Title: RE: 1500 pep output max
Post by: W6RZ on February 18, 2016, 06:20:08 AM
It's because of those high peaks that COFDM (Coded OFDM) was thought up. That specifically gets rid of those relatively few codes that need very high PEP.

That example was COFDM (specifically DVB-T2). These days most folks just say OFDM since it's pretty much all coded.

FEC (Forward Error Correction) coding has no effect on PAPR. I'm not sure where you got that idea. If you have a reference, I'd be interested to see it.

One of the advantages of DVB-T2 over DVB-T is that DVB-T2 offers two PAPR reduction techniques as part of the standard. They are Active Constellation Extension and Tone Reservation.

Here are the results of the very same transmission, but with Tone Reservation PAPR reduction applied. Tone Reservation PAPR reduction sets aside some unmodulated carriers to dump the excess energy of the large peaks into.

$ ./papr /media/re/ssd/dvbt2.cfile
Peak magnitude = 0.588524
average power = 0.041268, peak power = 0.346361 @ 27422699048

Maximum PAPR = 9.239128
percentage above 0 dB = 36.80828435
percentage above 1 dB = 28.41514388
percentage above 2 dB = 20.51123577
percentage above 3 dB = 13.60532080
percentage above 4 dB = 8.11607365
percentage above 5 dB = 4.23263430
percentage above 6 dB = 1.86483757
percentage above 7 dB = 0.66397905
percentage above 8 dB = 0.18081983
percentage above 9 dB = 0.03490846

peak real positive = 0.587104, peak imaginary positive = 0.581995
peak real negative = -0.582605, peak imaginary negative = -0.581996

peak real positive @ 27422699048, peak imaginary positive @ 3921111441
peak real negative @ 27422588960, peak imaginary negative @ 16727315209

Better, but still over 9 dB. At 1500 watts average, that's still 12 kW PEP.


Title: RE: 1500 pep output max
Post by: AA6CJ on February 18, 2016, 06:53:17 PM
It's because of those high peaks that COFDM (Coded OFDM) was thought up. That specifically gets rid of those relatively few codes that need very high PEP.

In SSB similarly it may be a transient peak that is of little to no benefit to speech intelligibility, and yet because it is present, it puts a power limit on the whole modulated waveform driving down average power.  PEP doesn't seem to serve a meaningful purpose, and may be all that was available to "easily" measure a SSB power back in the days.   For CW PEP is equal to average power.  It's akin to a laser beam focusing such power in such a small bandwidth.  I like CW a lot.


Title: RE: 1500 pep output max
Post by: G3RZP on February 19, 2016, 02:32:08 AM
Professor Steve Barton of Bradford (and later, Manchester) University did a lot of work on COFDM and optimum coding for minimising peak to average ratio:  I'm not sure where he published, and he also had some patents - which will have long expired now -  I was involved with this back in the days of the ETSI Hiperlan project in the early 1990s. Steve may even be dead by now - I know he retired some years back, and was somewhat older than I am. He did get some EU funding to pay for the work....but it's all a long time ago now


Title: RE: 1500 pep output max
Post by: W6RZ on February 19, 2016, 12:05:57 PM
Professor Steve Barton of Bradford (and later, Manchester) University did a lot of work on COFDM and optimum coding for minimising peak to average ratio:  I'm not sure where he published, and he also had some patents - which will have long expired now -  I was involved with this back in the days of the ETSI Hiperlan project in the early 1990s. Steve may even be dead by now - I know he retired some years back, and was somewhat older than I am. He did get some EU funding to pay for the work....but it's all a long time ago now

His paper "Asymptotic limits in peak envelope power reduction by redundant coding in orthogonal frequency division multiplex modulation" seems to be widely referenced in OFDM PAPR reduction research. Unfortunately, it required extra codeword bits and reduced the available payload rate. Also, it didn't scale well computationally to systems with a large amount of carriers (like DVB-T and DVB-T2 with 1024 to 32768 carriers).

When the BBC decided to move to DVB-T2, they worked with Ofcom to develop seven different transmission modes. Ofcom mode 3 has pretty deep tone reservation PAPR reduction. So deep that I can't run it in real-time on my Xeon workstation. In the end, they chose Ofcom mode 7 which doesn't have any PAPR reduction (in favor of a high 40.2 Mbps payload rate for the HD multiplexes).

http://stakeholders.ofcom.org.uk/binaries/spectrum/spectrum-policy-area/projects/dtv/BBC_submission_on_UK_transm1.pdf

Due to the availability of some low cost equipment from Taiwan, DVB-T is becoming popular for ham digital television in the US. But the high PAPR makes for difficult power amplification. 25 watt PEP amplifiers can only deliver a couple of watts of undistorted average power. I've been trying to understand the PAPR issue for a while now, and writing the PAPR analysis program has helped quite a bit.

http://www.hides.com.tw/product_eng.html


Title: RE: 1500 pep output max
Post by: W1BR on February 20, 2016, 08:44:49 AM

Egmont (YL3GND):

You're right!  I transposed Peak Power with Peak Envelope Power (PEP), which is defined as:

"Peak Envelope Power (PEP) is defined as the average power supplied to the antenna transmission line by a
transmitter during one radio frequency cycle at the crest of the modulation envelope

taken under normal operating conditions.”

So a pure sinusoid whose envelope amplitude does not vary will have a PEP power equal to its Average power.

Thank you for the correction!  (Ooops!)

Brian K6BRN



I think many others were as well.  Including myself.

Pete


Title: RE: 1500 pep output max
Post by: AA6CJ on February 20, 2016, 05:49:41 PM
Can someone provide a definition of "one radio frequency cycle"?


Title: RE: 1500 pep output max
Post by: QRP4U2 on February 20, 2016, 10:31:29 PM
Example 1: You're on 7.2 MHz (40m).

Every 0.138 microseconds the RF waveform repeats itself. It crosses zero, rises to a positive peak and goes back down to zero in 0.069 microseconds. It goes down to a negative peak and then goes back to zero in another 0.069 microseconds.

Example 3: You're on 3.5 MHz (80m).

Every 0.286 microseconds the RF waveform repeats itself as above.

http://www.sengpielaudio.com/calculator-period.htm

https://www.google.com/search?q=sine+wave&espv=2&biw=1258&bih=617&site=webhp&tbm=isch&tbo=u&source=univ&sa=X&sqi=2&ved=0ahUKEwjqip-EnYjLAhUD2R4KHcVyD2wQ7AkIVw&dpr=1.25#imgrc=LiZeJDe4dvUwTM%3A

Phil - AC0OB




Title: RE: 1500 pep output max
Post by: W3RSW on February 21, 2016, 04:41:15 AM
Well no wonder Avis people may be confused. FCC needs to update their language.


Title: RE: 1500 pep output max
Post by: AA6CJ on February 21, 2016, 02:59:24 PM
Phil,
When I read definitions of PEP they refer to the modulation envelope.  So is it possible that the period of RF cycle is set the modulation frequency bandwidth vs the carrier frequency?  It also was kind of inferred in the Eimac documentation referenced in one of the almost 300 posts. 


Title: RE: 1500 pep output max
Post by: QRP4U2 on February 21, 2016, 04:20:41 PM
Phil,
When I read definitions of PEP they refer to the modulation envelope.  So is it possible that the period of RF cycle is set the modulation frequency bandwidth vs the carrier frequency?  It also was kind of inferred in the Eimac documentation referenced in one of the almost 300 posts.  

Go back to Page 87 of the Eimac Document, and look closely at Figure 47. This is the Modulation Envelope.

Look closely at Page 91; those are Modulation Envelopes.

Those spikes ("hairs") within the Modulation Envelope are the RF cycles as explained above.

EIMAC Document   http://www.cpii.com/docs/related/22/C&F4Web.pdf

Other than that, I am not sure what you are asking.

Phil


Title: RE: 1500 pep output max
Post by: AA6CJ on February 21, 2016, 05:11:39 PM
See figure 45 that I think corresponds with 47.  Q:  does the modulation envelope correspond to 400 or 2500 hz components.  It seems to me that the RF cycle would be based on the modulation frequency not the carrier.


Title: RE: 1500 pep output max
Post by: QRP4U2 on February 22, 2016, 12:53:42 PM
See figure 45 that I think corresponds with 47.  Q:  does the modulation envelope correspond to 400 or 2500 hz components.  It seems to me that the RF cycle would be based on the modulation frequency not the carrier.

You're mixing apples and oranges.

Figs 44 through 46 are graphs of Amplitude verses Frequency, as in "Spectrum."

The other Figures, Figures 47-50,  are Modulation envelopes, which are Amplitude verses Time graphs.

Quote
SSB utilizes only one of the double sidebands of AM and also omits the carrier frequency transmission. The upper sideband SSB signal is illustrated here:

http://www.hamradioschool.com/understanding-single-sideband-ssb-2/

Quote
The trade-off with SSB as compared to conventional double-sideband AM and especially to FM phone mode is the quality of the audio. Narrower bandwidth dictates a reduction in audio information carried by the SSB signal as compared to the AM or FM signal. As a result, SSB audio will sound a bit thinner and less rich, but still quite intelligible and more than sufficient for weak signal phone communications.

Phil

 


Title: RE: 1500 pep output max
Post by: AA6CJ on February 22, 2016, 05:02:01 PM
Phil,
I do think in terms of spectrum, and I'm hoping you can help me understand what part 97 is actually saying.

Part 97 definition says:
(6) PEP (peak envelope power).  The average power supplied to the transmission line by a transmitter during one RF cycle taken at the crest of the modulation envelope under normal operating condition.

You've explained what one RF cycle is, but what would be considered the crest of the modulation envelope for SSB?  How does the Ssb spectrum modulated by the human voice figure into this?  Could you explain in simple terms what this means?

Fred


Title: RE: 1500 pep output max
Post by: W6RZ on February 22, 2016, 05:51:31 PM
@AA6CJ. See my post way back on page 7.

http://www.eham.net/ehamforum/smf/index.php/topic,106785.msg896042.html#msg896042


Title: RE: 1500 pep output max
Post by: QRP4U2 on February 22, 2016, 06:10:11 PM
@AA6CJ. See my post way back on page 7.

http://www.eham.net/ehamforum/smf/index.php/topic,106785.msg896042.html#msg896042


AAC6J See W6RZ's post he referenced above with the following quote:

Quote from: W6RZ
Zoom in another 5X. 200 microseconds of waveform. At this scale, we're starting to see individual RF cycles, but can still see part of the envelope.

Phil
 


Title: RE: 1500 pep output max
Post by: QRP4U2 on February 22, 2016, 06:14:56 PM
AA6CJ, you have to read my earlier post, Reply #265 on: January 29, 2016, 01:47:24 PM

Quote from: QRP4U2

It indeed can be measured accurately with the proper detector circuits such as the IC's I discussed, but not with slow thermal or diode envelope detectors that have long thermal or electrical time constants, respectively.

However, you can determine it with a calibrated storage scope.

Here is another try at the math (forget the two-tone tests for the moment that the manf. have to make during testing).

1) Let's say you have a "T" connector connected to your 50 ohm non-reactive dummy load and a storage scope with a probe monitoring the load.

2) You input a constant, maxiumum level voice recording into your SSB rig. You measure a maximum voltage somewhere over the snapshot's time period. At some point in the snapshot, you zoom in to the waveform and observe a maximum of 200 Volts Peak-to-Peak across the load.

3) PEP = V^2/R = (200V P-P/2 X 0.707)^2 / 50 = (100V X 0.707)^2 / 50 = 5000/50 =
100 W PEP power.

Now, 200V Peak-to-Peak voltage is the same voltage you would see with a high amplitude sine wave (or any audio wave of any shape) inputted to your SSB rig and the PEP would still be 100 Watts PEP.

But here is the catch: In normal voice situations, this peak envelope power rarely occurs. In fact, with normal unprocessed voice, the Peak Envelope Power may only be 25-33 Watts PEP.

Phil




Title: RE: 1500 pep output max
Post by: AA6CJ on February 23, 2016, 04:33:02 PM
@AA6CJ. See my post way back on page 7.

http://www.eham.net/ehamforum/smf/index.php/topic,106785.msg896042.html#msg896042


Thank you W6RZ, it is very clear. 


Title: RE: 1500 pep output max
Post by: AA6CJ on February 23, 2016, 04:51:00 PM
Phil,
...
Part 97 definition says:
(6) PEP (peak envelope power).  The average power supplied to the transmission line by a transmitter during one RF cycle taken at the crest of the modulation envelope under normal operating condition.
...
You and w6rz have clarified the RF cycle.  Thanks.  "...under normal operating condition..." Is ambiguous. W6rz used a single word in his example. Is this normal?

At hf frequencies the RF cycle is so short, and the time period of the envelope so ambiguous, that I am having a hard time seeing how PEP is a good measure of Ssb power. It isn't setting well with me at all.  I don't see an alternative yet.  Do you?


Title: RE: 1500 pep output max
Post by: N0GW on February 24, 2016, 07:07:46 AM
"At hf frequencies the RF cycle is so short, and the time period of the envelope so ambiguous, that I am having a hard time seeing how PEP is a good measure of Ssb power. It isn't setting well with me at all.  I don't see an alternative yet.  Do you?"

Sorry it isn't setting well with you.  What you are describing is simply the difference between Peak Envelope Power and "Average Envelope Power".  (I just made that term up!)  Yes, the SSB envelope waveform shows many peaks of many different amplitudes.  Which peaks do you use to determine your PEP?  That is easy.  It is the it is the highest ones.  Nominally, with a typical 100 watts transceiver, those highest peaks will be at the 100 watts RMS peak-to-peak voltage.  That, of course means that those lower peaks are below 100 watts.  That is the basic physics of un-processed voice SSB.  The Average Envelope Power is usually 25% to 35% of Peak Envelope Power.

Various methods are employed to process audio and SSB envelopes to improve the average to peak power ratio and thus make a louder, easier to copy under poor propagation conditions, signal.  Some are quite successful.  Keep in mind that even with SSB average power only about one third its PEP value, a 100 watt PEP SSB signal usually performs better at a distant location than a 100 watt full carrier NBFM signal.  Even on VHF, DX stations run SSB.

You say you are having a hard time accepting that PEP is a good measure of SSB power.  In fact, it is the only practical way to define it.  Let's say you come of with some time constant for averaging voice SSB power.  For the sake of argument, let's say 1 second.  Now, you pick up the microphone and transmit a nice long "Hellooooooooo" and adjust your output power to 1500 indicated watts.  All good now?  What will you see on that meter when you say "one, two, three, four."  What happens if you whistle into the mic?  3000 to 4000 watts out is what you would see provided your amplifier would not go into peak clipping causing splatter or simply blow up.

As many folks have already said, measuring waveform peak power (thus PEP) is not difficult or complex.  A simple voltage detector with a slow voltage decay is all that is necessary.  The tricky part is not the circuitry to capture the peak voltage, it is coming up with a detector that you can leave in line without introducing a high loss or impedance bump.  That same detector would be needed for any kind of averaging detector, as is the case with those non-PEP RF wattmeters we use.

This is all stuff that has been worked out decades ago.


Title: RE: 1500 pep output max
Post by: W1BR on February 24, 2016, 08:39:09 AM
The confusion for most is that every RF cycle should be a sinusoidal waveform due to the flywheel effect of a PA tank of reasonable Q.

Using peak voltage  (instead of RMS voltage, for any AC voltage produced by a RF generator delivering a sinusoidal waveform) to calculate power seems to be something audiofools would use to exaggerate actual meaningful power ratings.

Why peak power isn't determined by the maximum peak AC voltage times .707 is very confusing.

Pete
 


Title: RE: 1500 pep output max
Post by: N0GW on February 24, 2016, 09:54:06 AM
"Why peak power isn't determined by the maximum peak AC voltage times .707 is very confusing."

Pete,

That is exactly the way it is done.  In the case of the Oscilloscope trace, you multiply the peak-to-peak voltage by .3535 to get the RMS voltage to calculate the power for a given resistance. (or .707 of the peak voltage if you prefer - remember, peak is 1/2 peak-to-peak for a sine wave).  That RMS voltage of the sine wave at the peak of the SSB waveform is used to calculate the PEP power.  Though the diode in at RF power meter does not know RMS from PMS, there is a simple linear relationship between peak-to-peak (or peak) voltage and RMS voltage.  That is taken into account when the meter is calibrated to indicate RF power.

To restate it:  Peak Envelope Power is calculated based upon the RMS voltage at the highest peak or crest of the SSB waveform.  Both an oscilloscope and a diode detector respond to peak-to-peak or peak voltage depending upon the circuit.  We calculate the RF power of that waveform by calculating the RMS equivalent of that voltage, either by direct calculation or by how we mark the scale on a power meter.

That clarify it?

Gary - N0GW


Title: RE: 1500 pep output max
Post by: N4RSS on February 24, 2016, 12:59:32 PM
"Why peak power isn't determined by the maximum peak AC voltage times .707 is very confusing."

Pete,

That is exactly the way it is done.  In the case of the Oscilloscope trace, you multiply the peak-to-peak voltage by .3535 to get the RMS voltage to calculate the power for a given resistance. (or .707 of the peak voltage if you prefer - remember, peak is 1/2 peak-to-peak for a sine wave).  That RMS voltage of the sine wave at the peak of the SSB waveform is used to calculate the PEP power.  Though the diode in at RF power meter does not know RMS from PMS, there is a simple linear relationship between peak-to-peak (or peak) voltage and RMS voltage.  That is taken into account when the meter is calibrated to indicate RF power.

To restate it:  Peak Envelope Power is calculated based upon the RMS voltage at the highest peak or crest of the SSB waveform.  Both an oscilloscope and a diode detector respond to peak-to-peak or peak voltage depending upon the circuit.  We calculate the RF power of that waveform by calculating the RMS equivalent of that voltage, either by direct calculation or by how we mark the scale on a power meter.

That clarify it?

Gary - N0GW


So if you use RMS voltage as you describe above and divide by R, you've calculated average power, per its definition


Title: RE: 1500 pep output max
Post by: N0GW on February 24, 2016, 04:21:07 PM
"So if you use RMS voltage as you describe above and divide by R, you've calculated average power, per its definition"

Well, yes, sorta.  Given the amount of confusion on this thread I'd like to be a little more specific.  I think I would write that as:

"So if you use RMS voltage as you describe above squared and divide by R, you've calculated power for that voltage, per its definition"

Saying "average power" is more than a little ambiguous in this conversation.  It is correct if you are meaning the power averaged through one cycle of RF voltage and current.  It is not correct if you are meaning the average of the SSB speech waveform.  In general when we are discussing RF power and SSB, "average power" is usually meant to be the average over some significant time period, usually something like the length of a full sentence of speech.  We use the term Peak Envelope Power as the highest instantaneous (one RF cycle) power generated by a transmitter during that sentence.  (Let's not get wrapped up in the duration of the average - I'm presenting the general concept here.)

As a quick refresher, when comparing the 100 % modulated AM and the same Peak Envelope Power SSB signal, remember that only 33% of the AM transmitter's power is modulation information.  100 watts PEP 100% modulated AM produces 33 watts of sideband power.  66% is the carrier that does not convey information.  The 100 watt PEP SSB transmission is 100 percent information.  (OK, let's not get into a discussion of the conversations we hear on the air are conveying information - by information, we actually mean the desired transmission information - regardless of its value to the receiving parties ;-)  )


Title: RE: 1500 pep output max
Post by: AA6CJ on February 24, 2016, 05:55:57 PM
In general when we are discussing RF power and SSB, "average power" is usually meant to be the average over some significant time period, usually something like the length of a full sentence of speech.  We use the term Peak Envelope Power as the highest instantaneous (one RF cycle) power generated by a transmitter during that sentence.  (Let's not get wrapped up in the duration of the average - I'm presenting the general concept here.)

I take it from your comment that you are an RF engineer.  This thread was started asking the question whether average power would be better to measure vs PEP given that other modes like CW and RTTY average power is equal to PEP while Ssb average power is 25-33% of PEP.  Based on your discussions about average power you refer to above, and going along with using a "significant time period" as an averaging time constant, why is PEP preferable for our ham radio use? 

I see this as a discussion of power parity between modes...


Title: RE: 1500 pep output max
Post by: N0GW on February 24, 2016, 07:38:29 PM
"I see this as a discussion of power parity between modes..."

Interesting..  I kinda assumed that was the original question but folks were going off into the weeds figuring out what Peak Envelope Power means.

Now, you will have to define what you think parity between modes might be.  Do you mean that all modes should be given a power level that allows them the same communications capability at some distant point on the earth?  What is the base reference?  JT65, PSK31, SSB voice, Full Carrier AM, NBFM, Spread Spectrum?  I'm not trying to be silly here but what are you concerned about SSB achieving parity with?

Obviously each mode has different communications capability under different propagation and noise conditions.  I saw reference earlier to comparing the average power of RTTY with the average power of SSB.  RTTY is a 100% average power mode.  Under most conditions a 1500 watt PEP SSB signal gets through better than a 1500 watt RTTY signal.  That difference is why RTTY stations typically run high power.  It is necessary even with modern computer based decoding programs.  On the other hand, a 150 watt PSK31 signal would likely get through more reliably than a 1500 watt SSB signal.  Most PSK31 operation is with power levels below 50 watts and world wide DXing is possible.  Each mode has its advantages and disadvantages for different purposes and under different conditions.

So, the question is: Parity with what?

Gary - N0GW





Title: RE: 1500 pep output max
Post by: K4KYV on February 25, 2016, 12:26:47 AM
In general when we are discussing RF power and SSB, "average power" is usually meant to be the average over some significant time period, usually something like the length of a full sentence of speech.  We use the term Peak Envelope Power as the highest instantaneous (one RF cycle) power generated by a transmitter during that sentence.  (Let's not get wrapped up in the duration of the average - I'm presenting the general concept here.)

To be meaningful, the term "average" power must be integrated over a defined time period that is relevant to the quantity being measured.  For example,  with CW, we could mean the average power over an entire transmission, which would include spaces between characters, words and sentences.  We could even define it as the average power over a QSO, including periods of reception.  Obviously, those definitions would have little meaning in terms of effective transmitter output power.  The chosen time period must be relevant to the nature of the transmitted data.  With CW, the relevant time period would be the duration of the shortest character of the normally transmitted  signal, i.e. a single dit.  With SSB voice, the relevant factor would be a function of the syllabic rate of human speech.

With SSB voice under the 1 KW DC input rule, the FCC addressed the issue of "input power" in a letter to ARRL:

  The following ... may be considered as a presently acceptable method for determining the d.c. plate power input to the final r.f. stage of a single-sideband  amateur transmitter:
  The maximum d.c. plate power input to the (RF) tube(s) supplying power to the antenna system of a (SSB) suppressed-carrier transmitter, as indicated by the usual plate voltmeter and plate milliammeter, shall be considered as the "input power" insofar as ... the Commission's rules are concerned, provided the plate meters utilized have a time constant not in excess of approximately 0.25 second, and the linearity of the transmitter has been adjusted to prevent the generation of excessive sidebands.  The "input power" shall not exceed one kilowatt on peaks as indicated by the plate meter readings.


- Single Sideband for the Radio Amateur (ARRL), second edition 1958, page 14

Average output power from a transmitter is generally proportional to the DC input to the final stage, assuming a consistent efficiency factor. That was the basis for the amateur power limit for many decades and served the purpose well. The 0.25 second (250 ms) time constant prescribed in the FCC statement is consistent with the concept of the audio V-U meter used  in audio recording and broadcasting, in which by definition the mass of the meter movement effectively integrates the signal with a rise time of 300 ms.

Here is a treatise which may be of interest, from the BBC in 1963, on the subject of VU meters, peak-reading meters and loudness measurements:
http://www.mwigan.com/mrw/Publications__49_Edmund_Ramsay_Wigan_files/1963-29.pdf


Title: RE: 1500 pep output max
Post by: W1BR on February 25, 2016, 07:55:45 AM
Which begs the question, if a CW transmitter has ALC overshoot, does the peak power of the transient define the peak power for that situation?

Pete


Title: RE: 1500 pep output max
Post by: M0HCN on February 25, 2016, 09:25:30 AM
Average output power from a transmitter is generally proportional to the DC input to the final stage, assuming a consistent efficiency factor. That was the basis for the amateur power limit for many decades and served the purpose well.
The problem is that if you throttle a PA back by say 10dB without changing the loading, the input power will only fall by a factor of about 3 (square root of 10).... The assumption of linearity does not hold here unless you are changing the load impedance or supply voltage to track the envelope, peak output may be generally proportional to peak input, but this does not in general follow for the average values.

VU and even PPM are largely history in broadcast these days, the BS1770-3 loudness meter being the weapon of choice, but it says little to nothing about instantaneous power, perceived loudness having little to do with peak power in typical program material. I would note that for SSB, the real valued audio envelope and the RF envelope are not the same thing, as the RF envelope is bounded by Sqrt (I^2 + Q^2), not simply by I.

PEP seems to me to be a perfectly reasonable way of slapping a limit on transmitters which can operate in many, many different modes, some having constellation diagrams that are almost constant power  (RTTY, PSK) and some having horrible peaks in the envelope (OFDM, SSB), the alternative is to have the regulator having to set different rules for each mow mode somebody comes up with.

Now personally a DC input limit holds a certain appeal, it puts the emphasis on getting clever with the design again, and we might start seeing things more interesting then the usual class AB stuff that everyone and their dog makes (Doherty, EER, harmonic tuning).

Silly thought but how about a limit in terms of power per Hz of occupied bandwidth (After all, that is how we measure the system noise), so CW (With maybe ~30Hz of occupied bandwidth) would have a limit of 15W, while SSB (3KHz occupied bandwidth) would have a limit of 1,500W... I can hear the screaming from here!

73 Dan.


Title: RE: 1500 pep output max
Post by: G3RZP on February 25, 2016, 11:51:05 AM
Quote
Silly thought but how about a limit in terms of power per Hz of occupied bandwidth (After all, that is how we measure the system noise), so CW (With maybe ~30Hz of occupied bandwidth) would have a limit of 15W, while SSB (3KHz occupied bandwidth) would have a limit of 1,500W... I can hear the screaming from here!

That allows more occupied bandwidth. Better would be the inverse so 15 watts for 3kHz and 1500 for 30 Hz - and 3000 for 15 Hz!


Title: RE: 1500 pep output max
Post by: M0HCN on February 25, 2016, 01:05:45 PM
But the noise power in 3Khz bandwidth is inherently greater then that in 30Hz...

Maybe go with something creative, allowed power is exponential in how close you get to the limit in the telegraphers Eqn, after all, the more intelligence you manage to cram in per joule, the more efficiently you are using the spectrum?

Something clever with COFDM, FEC and viterbi decoders should be allowed more power then something only managing a few kb/s in 3KHz, because it is surely moving more data for its bandwidth? Kind of hard to build a simple meter for that however, so PEP (Or DC input) is probably a good choice.

73 Dan.


Title: RE: 1500 pep output max
Post by: AA6CJ on February 26, 2016, 07:33:54 PM
In general when we are discussing RF power and SSB, "average power" is usually meant to be the average over some significant time period, usually something like the length of a full sentence of speech.  We use the term Peak Envelope Power as the highest instantaneous (one RF cycle) power generated by a transmitter during that sentence.  (Let's not get wrapped up in the duration of the average - I'm presenting the general concept here.)

To be meaningful, the term "average" power must be integrated over a defined time period that is relevant to the quantity being measured.  For example,  with CW, we could mean the average power over an entire transmission, which would include spaces between characters, words and sentences.  We could even define it as the average power over a QSO, including periods of reception.  Obviously, those definitions would have little meaning in terms of effective transmitter output power.  The chosen time period must be relevant to the nature of the transmitted data.  With CW, the relevant time period would be the duration of the shortest character of the normally transmitted  signal, i.e. a single dit.  With SSB voice, the relevant factor would be a function of the syllabic rate of human speech.

With SSB voice under the 1 KW DC input rule, the FCC addressed the issue of "input power" in a letter to ARRL:

  The following ... may be considered as a presently acceptable method for determining the d.c. plate power input to the final r.f. stage of a single-sideband  amateur transmitter:
  The maximum d.c. plate power input to the (RF) tube(s) supplying power to the antenna system of a (SSB) suppressed-carrier transmitter, as indicated by the usual plate voltmeter and plate milliammeter, shall be considered as the "input power" insofar as ... the Commission's rules are concerned, provided the plate meters utilized have a time constant not in excess of approximately 0.25 second, and the linearity of the transmitter has been adjusted to prevent the generation of excessive sidebands.  The "input power" shall not exceed one kilowatt on peaks as indicated by the plate meter readings.


- Single Sideband for the Radio Amateur (ARRL), second edition 1958, page 14

Average output power from a transmitter is generally proportional to the DC input to the final stage, assuming a consistent efficiency factor. That was the basis for the amateur power limit for many decades and served the purpose well. The 0.25 second (250 ms) time constant prescribed in the FCC statement is consistent with the concept of the audio V-U meter used  in audio recording and broadcasting, in which by definition the mass of the meter movement effectively integrates the signal with a rise time of 300 ms.

Here is a treatise which may be of interest, from the BBC in 1963, on the subject of VU meters, peak-reading meters and loudness measurements:
http://www.mwigan.com/mrw/Publications__49_Edmund_Ramsay_Wigan_files/1963-29.pdf


How cool that you digged up this FCC statement.  The .250 ms time constant could still be used today and applied to PEP output.  The BBC paper makes a good case for PPM vs VU, But ignoring that for now....  I wonder how much increase in average power would result?  If someone had simulink it might be pretty straight forward to analyze.


Title: RE: 1500 pep output max
Post by: AA6CJ on February 26, 2016, 07:44:20 PM
PEP seems to me to be a perfectly reasonable way of slapping a limit on transmitters which can operate in many, many different modes...

Silly thought but how about a limit in terms of power per Hz of occupied bandwidth...
73 Dan.
Agreed and not silly.  However, 1500 watts concentrated in a 30hz CW...is akin to a laser beam.  I could see one getting addicted to power like that.  Hi!


Title: RE: 1500 pep output max
Post by: AA6CJ on February 26, 2016, 07:51:16 PM
"I see this as a discussion of power parity between modes...Now, you will have to define what you think parity between modes might be.  Do you mean that all modes should be given a power level that allows them the same communications capability at some distant point on the earth?  What is the base reference?  JT65, PSK31, SSB voice, Full Carrier AM, NBFM, Spread Spectrum?  I'm not trying to be silly here but what are you concerned about SSB achieving parity with?

Obviously each mode has different communications capability under different propagation and noise conditions.  I saw reference earlier to comparing the average power of RTTY with the average power of SSB.  RTTY is a 100% average power mode.  Under most conditions a 1500 watt PEP SSB signal gets through better than a 1500 watt RTTY signal.  That difference is why RTTY stations typically run high power.  It is necessary even with modern computer based decoding programs.  On the other hand, a 150 watt PSK31 signal would likely get through more reliably than a 1500 watt SSB signal.  Most PSK31 operation is with power levels below 50 watts and world wide DXing is possible.  Each mode has its advantages and disadvantages for different purposes and under different conditions.

So, the question is: Parity with what?

Gary - N0GW

I expected this question.  All valid points.  As I understand it in the PSK31 it would be considered terrible manners and completely unnecessary to run high power.


Title: RE: 1500 pep output max
Post by: K4KYV on February 27, 2016, 09:54:55 PM
How cool that you digged up this FCC statement.  The .250 ms time constant could still be used today and applied to PEP output.  The BBC paper makes a good case for PPM vs VU, But ignoring that for now....  I wonder how much increase in average power would result?  If someone had simulink it might be pretty straight forward to analyze.

Or more meaningfully, to average power.  It would be based on a true-RMS reading RF voltmeter or ammeter, with no more than a 0.250 time constant. The thermocouple RF ammeter is too sluggish, so it would likely be accomplished with some type of active DSP circuit.  Problem with the "average power" function with conventional meters like the Bird 43, is that it actually reads simple average voltage rectified with a diode, not true RMS. What confuses most people is that average power is derived from RMS voltage/current, NOT average (absolute value of) voltage/current. And, as we discussed before, there is no such thing as RMS power or RMS watts, and average voltage X average current yields a physically meaningless figure.


Title: RE: 1500 pep output max
Post by: AA6CJ on February 28, 2016, 05:13:19 PM

Or more meaningfully, to average power.  It would be based on a true-RMS reading RF voltmeter or ammeter, with no more than a 0.250 time constant.

I understand.  I'm not aware of such a wattmeter.  If anyone does please let me know. Thanks.

Addendum - MB-1 will work.


Title: RE: 1500 pep output max
Post by: KM1H on March 03, 2016, 06:20:50 PM
Quote
I expected this question.  All valid points.  As I understand it in the PSK31 it would be considered terrible manners and completely unnecessary to run high power.

As an absolute statement....WHY? Plus it is only for HF as at VHF thru microwave and EME they often run full bore 1500W or as much as they can get...plus or minus ::)

Granted there is a ~ 20dB advantage over CW but do you really think serious DX stations at both ends wont run 1500W or so and pick up another 10-12db or so out of the noise?

Talk about working the world on an apparently, by ear, dead band and creating your own propagation!

Let the QRP JT users have their little band segments, Im sure it is fun for that mind set. Ive already confirmed 9BDXCC with a QRP 5W on CW but it took 30 years to do it on 160. So far Ive no interest in any of the digi modes but might give it a try when the 630M ham band is authorized in the US since only 5W ERP will be allowed.

Carl


Title: RE: 1500 pep output max
Post by: AA6CJ on March 03, 2016, 07:43:30 PM
As an absolute statement....WHY? Plus it is only for HF as at VHF thru microwave and EME they often run full bore 1500W or as much as they can get...plus or minus ::)

Granted there is a ~ 20dB advantage over CW but do you really think serious DX stations at both ends wont run 1500W or so and pick up another 10-12db or so out of the noise?

Talk about working the world on an apparently, by ear, dead band and creating your own propagation!
I confess that harbor a HF centric point of view.  When we go back to solar minimum, I'm thinking about giving the higher bands and EME a go.   :)


Title: RE: 1500 pep output max
Post by: KK4YDR on March 03, 2016, 10:06:51 PM
This thread has gotten so large it is impossible to keep up with it.


Title: RE: 1500 pep output max
Post by: K6UJ on March 09, 2016, 10:07:13 AM
This thread has gotten so large it is impossible to keep up with it.


Eric,

We are going for the longest thread award   ;D ;D ;D ;D

Bob
K6UJ


Title: RE: 1500 pep output max
Post by: K6CKD on March 10, 2016, 09:21:33 AM
Lets go back to the old days.  Input power.  Voltage times current. That made since.  From what I see,  add about 20% to the key down SSB power and you have PEP. Why do they want to complicate things.
What was wrong with kilocycle,  why does it have to be Hertz.
Whats with the call signs.  I heard a KJ the other day,  that used to be Johnson Island.  KG used used be the Mariana Islands.  Who knows what it is now.


Title: RE: 1500 pep output max
Post by: N6YW on April 07, 2016, 08:48:35 AM
This has been an enormously entertaining and remarkable thread. I appreciate the brain trust who
set fine examples of truth verses fantasy. Of particular note was the firm handed technical spanking
that was applied to El Brino HaRO. Perhaps he will use that as an excuse to deflate his enormous ego
and take stock of his insecurities, and who knows, MAYBE consider not being a keyboard bully as his
history on the boards so well illuminates. It's a pity he has no one to circle the wagons on his behalf.
But then, that usually happens to those who behave like that and for good reason... something that he
doubtfully will ever embrace.
Thank you for the lessons.
73 de Billy N6YW
"Life is too short for QRP"