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Author Topic: S-Meter accuracy...LED or needle types  (Read 10712 times)
K0OD
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Posts: 2521




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« Reply #15 on: August 21, 2012, 03:58:34 PM »

Like that ADAT?  Here... you can be the 76th member of that Yahoo Group

http://groups.yahoo.com/group/adat/
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K2OWK
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Posts: 1036




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« Reply #16 on: August 21, 2012, 04:17:45 PM »

S meters are good for a reference source. They are really not needed everyone just says 599 if they hear you. No reply if they don't. In the old days we would give the S meter reading S4, S6, S9, 20 over etc. Q5 meant quality 5 perfectly clear audio. Now 599 is the norm regardless of the signal strength or the quality.

5/9 voice 5/99 CW.

73s

K2OWK
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AA4PB
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Posts: 12665




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« Reply #17 on: August 22, 2012, 05:28:20 AM »

Since most modern rigs contain a microprocessor (even non-SDR), having a calibrated S-meter is not as difficult as it used to be. The calibration (per band, pre-amp on or off) can be done in firmware. The biggest issue is probably that somebody has to spend the time to do the calibration and it needs to be redone periodically to account for changes caused by ageing components.
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KC9TNH
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Posts: 304




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« Reply #18 on: August 22, 2012, 01:12:50 PM »

Having read the well-published table when getting my civ amateur license (coming from 5x5 being the ultimate) I once gave someone I with whom I was having a perfectly good conversation a 45. Holy Emotional Events, Batman!

I have a couple of Yaesu's on the table so the 'S-' stands for stingy.
 Cheesy
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73
Wes -KC9TNH
"Don't get treed by a chihuahua." - Pete
W4OP
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Posts: 392


WWW

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« Reply #19 on: August 22, 2012, 05:55:48 PM »

Like that ADAT?  Here... you can be the 76th member of that Yahoo Group

http://groups.yahoo.com/group/adat/

Good grief, all I said was that it had a calibrated S meter.
Dale W4OP
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STAYVERTICAL
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Posts: 854




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« Reply #20 on: August 23, 2012, 01:20:24 AM »

Like that ADAT?  Here... you can be the 76th member of that Yahoo Group

http://groups.yahoo.com/group/adat/

Good grief, all I said was that it had a calibrated S meter.
Dale W4OP

You did it Dale, you broke the rule " He who shall not be named".
Now Voldemort is looking for you.

73 - Rob
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G3RZP
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Posts: 4356




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« Reply #21 on: August 23, 2012, 01:53:50 AM »

Even if it is well calibrated, unless you know the applicable antenna factor, it doesn't really tell you very much.
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ZENKI
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Posts: 906




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« Reply #22 on: August 24, 2012, 01:55:05 AM »

If it was properly calibrated you would have a realistic idea of what the noise level at your QTH is. Unlike the 10,000 dollar radio manufacturers who deliberately compress the bottom end of the S-meter scale so it looks like you have a
low noise QTH.  A calibrated S-meter would  also would  give you a true indication of galactic noise on the higher bands which on a dipole antenna in 2.4khz bandwidth  should be something from S3 to around  S1 on a calbrated S-meter.

Radios should have their pre-amp settings with labels like Quiet Rural, Suburban, City, and Industrial. This way you can set the gain of the receiver to the noise floor of the location using just the right amount of sensitivity.
The worst feature of modern radios is the excess gain on the lower bands that is really  not needed or cant be realistically exploited. Its pointless amplifying galactic noise and QRM.

Talking about antenna factor and other factors. If the receivers did have calibrated S-meters, Antenna factor offset, EMC 9khZ bandwidth plus Quasi peak detectors we could use our radios as legitimate EMC receivers for measuring
radiated  emissions and reporting these levels.  We have 10,000 dollar radios with useless S-meters that are as bad as 50 dollar CB radios, why are we paying such high prices for expensive junk? I can buy a Rigol spectrum Analyzer for 2000 US dollars that is accurate to within 0.3db with a color screen. Why  do useless radios like the Icom IC7700 and IC7800 cost so much and are nothing more than useless toys with a meter that us totally useless?

Calibrated S-meters are very handy if designed and implemented correctly to be a true reference 50 ohm source impedance level meters. This  should be easily accomplished in software defined radios.

It would be nice having S-meter in radios that can be switched to the commonly used scales such as Dbm, DbUv, S-units, Uv. Just about every commercial radio that I have used has an RSSI(received signal strength indicator) that is calibrated. Only hams buy 10,000 dollars pieces of equipment with 10,000 % inaccuracy. We should demand better.


The ADAT radio has the most accurate S-meter that I  have ever used. The K3 is reasonably good, however its resolution is limited to chunky S-units. All my SDR receivers, Perseus and Winradio have super accurate S-meters
The is absolutely no reason why a  Analog S-meter cannot  be made to closely match a LED bargraph for level indication. High speed wide bandwidth op amps are cheap these days. But I suppose it depends what you are actually measuring, deep fades of 20 db or following voice peaks, it depends on the application. With the appropriate sampling and detection algorithms, every possible  measurement should be able to be plotted and displayed.

Anyway dont expect  calibrated S-meters from ham companies any time soon, they committed to delivering the same radios with poor TX IMD, poor receivers and uncalibrated S-meters year after year. Its only because hams
appear to be consumer suckers.  We really deserve what we get because we dont complain about anything and just take the junk that they manufacture.

You have more chance of getting decent ham equipment from groups such as the HPSDR groups who understand these issues more than the manufacturers who are just in it for the money and not the science.

Its a real pity ADAT is not more proactive about marketing its radio. In my opinion this  one of the best pieces of  equipment a ham can buy for the money, its a true test receiver. Its transmitter is almost perfect with very low TX IMD.
They have such a good product, I dont know why they dont point a good marketing company like DXENGINEERING  in the USA to  market their products. I am sure it would be top seller in the USA. The S-meter is godly accurate.




Even if it is well calibrated, unless you know the applicable antenna factor, it doesn't really tell you very much.
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K1CJS
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Posts: 5850




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« Reply #23 on: August 24, 2012, 04:14:50 AM »

One thing not mentioned yet (except by the originator) is the time difference between the two types of s-meters.  The analog meter may lag a bit but it will show the actual reading better.  The electronic LED meter responds so quickly that you may miss a spike that the analog meter would show.

There can't really be a set standard because of the differences in the sensitivity of the different radios--even between two identical radios. 
« Last Edit: August 24, 2012, 04:17:03 AM by K1CJS » Logged
AA4PB
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Posts: 12665




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« Reply #24 on: August 24, 2012, 08:00:41 AM »

LED meters can have any response time you like if you design the circuit correctly.
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G3RZP
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Posts: 4356




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« Reply #25 on: August 24, 2012, 08:12:32 AM »

Strange thing about the ADAT radio is that there's no mention of what standards it meets. For Europe, it needs to meet EN301 489-1, EN301 489-15, EN301 783-1 and EN301 783-2.

Also it specifies spurious emissions beyond +/- 200 kHz, but the limits are +/-10kHz.
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K1CJS
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Posts: 5850




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« Reply #26 on: August 25, 2012, 06:32:32 AM »

LED meters can have any response time you like if you design the circuit correctly.

The LED meters still can't show a spike correctly because they respond so quickly.
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ZENKI
Member

Posts: 906




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« Reply #27 on: August 26, 2012, 02:54:41 AM »

They can if they have proper peak detector and sample and hold circuits.


LED meters can have any response time you like if you design the circuit correctly.

The LED meters still can't show a spike correctly because they respond so quickly.
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K1CJS
Member

Posts: 5850




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« Reply #28 on: August 26, 2012, 06:56:09 AM »

Now your getting from the sublime to the ridiculous.  It is true that LED meters can be made to show a peak while still showing the second by second signal just as it is done on the more expensive audio gear, but then the costs of manufacture go up.  You really think that the manufacturers are going to put such a meter in every rig--for the less than one percent of the users who may want it--or actually use it?

It they're going to do that, it probably would be mose cost effective for them to use analog meters--and we've seen already where that's gone--simply by looking at how many rigs now have the LED meters.
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AA4PB
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Posts: 12665




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« Reply #29 on: August 26, 2012, 07:54:10 AM »

I would think that a couple of ICs for a peak detector and an LED meter would be less expensive to mfg than a decent quality analog meter.
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