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Author Topic: S-Meter accuracy...LED or needle types  (Read 13146 times)
ZENKI
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Posts: 980




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« Reply #30 on: September 07, 2012, 04:06:16 AM »

Thats correct, analog meter manufacturers are disappearing fast. The Chinese factories produce garbage and who really would want to depend on a Chinese manufactured mechanical meter?

Peak detector circuits or even a high speed A/D converter can sample the signal voltage anyway you want and present the data in umpteen formats for display. These is absolutely no reason why ham radio
receiver should have the crap S-meters like they have on them today. They should all be calibrated considering the price that we are paying for radios. Its just pathetic reasoning  and making excuses for the manufacturers by saying
that producing a calibrated S-meter  is somehow rocket science and expensive.

As for the arguments  that S-meters are not meant to be exact and only relative, this is just a nonsense argument by people who have no idea what  a calibrated S-meter could be used for and how useful it could be.
More hams are partial too inaccurate  S-meters because they think people are fooled by silly and ridiculous reports. They somehow use inaccurate reports to make others believe that their stations and  antennas are working better
than some other hams. This kind of behavior is really evident by stations whose licensed restricts them to a very low output power. Giving idiotic reports seems to make them believe that they covering up their breach of their  license power rules by inferring that their stupid signal reports is their great antenna.  Experienced hams can see through this act of technical deficit disorder.


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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K7KBN
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Posts: 2825




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« Reply #31 on: September 07, 2012, 05:40:20 PM »

My first receiver didn't have a meter at all - it was a GE console AM broadcast receiver (pre-television), with a "short wave" band thrown in.  I could tell if a station was loud or not.  My next receiver was an SX-99.  I never bothered looking at the S-meter.  It moved fine and probably indicated something, but I could still tell if a station was loud or not.

If you guys are so adept, why not invent an S-meter that plugs into ANY radio and gives an absolute "S" reading referenced to anything the operator might want.  I'll keep using my ears to tell me if the other station is loud or not.
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73
Pat K7KBN
CWO4 USNR Ret.
G3RZP
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Posts: 4834




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« Reply #32 on: September 08, 2012, 01:21:53 AM »

The S meter can be useful as a relative strength indicator - for example, when switching between antennas. On the very few occasions that I want to make noise measurements, I either use the spectrum analyser, or calibrate the receiver with a signal generator for what I need.

Of course, it's not quasi peak - which is a very artificial thing derived from attempts to quantify noise into European AM receivers in about 1934 - and in any case, there is now a start to move away from QP in both ETSI and ITU.

There are, to my mind, too many attempts these days to make something for which there is a German term that translates roughly as ' egg laying milk producing pig that swims'. Scroggie's Radio Laboratory Handbook of the 1940s points out the dangers of that approach...
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K1CJS
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« Reply #33 on: September 08, 2012, 08:21:09 AM »

....These is absolutely no reason why ham radio receiver should have the crap S-meters like they have on them today. They should all be calibrated considering the price that we are paying for radios. Its just pathetic reasoning  and making excuses for the manufacturers by saying that producing a calibrated S-meter is somehow rocket science and expensive....

There are reasons, some of which are problematical and some aren't.

First, calibrated to what?   The differences in the various rigs and the wide selection of antennas make 'calibrated' meters useless.  Say, for example, that you've got a 'gain' type antenna.  How do you calibrate the meter so you can get an accurate reading on the station you're receiving?  What if that station is using such an antenna?  There is no possible way of having a meaningful standard!

Second, hams are notoriously a cheap bunch.  A small percentage may want such a meter, but how do you justify the cost of such a thing to the rest?

Third, look at the D-Star standard.  Icom embraced it, but the other two of the big three didn't.  How are you going to get ALL manufacturers to conform to one standard for S meters if they won't do that for more important developments?

We would be better off stopping trying to make something out of this.  An S-meter shows relative signal strength, not exact signal strength.  Why not let it go at that--and stop worrying about trying to re-invent the wheel!
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N3OX
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« Reply #34 on: September 08, 2012, 02:36:56 PM »

First, calibrated to what?   

Hard to beat dBm. 
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
G3RZP
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Posts: 4834




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« Reply #35 on: September 08, 2012, 03:11:47 PM »

And at the end of the day, what does it tell you? So it's so many dBm. So what?
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YO9IRF
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Posts: 29


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« Reply #36 on: September 08, 2012, 11:08:17 PM »


...

First, calibrated to what?   The differences in the various rigs and the wide selection of antennas make 'calibrated' meters useless.  Say, for example, that you've got a 'gain' type antenna.  How do you calibrate the meter so you can get an accurate reading on the station you're receiving?  What if that station is using such an antenna?  There is no possible way of having a meaningful standard!
...


The S-Meter is a tool that indicates the signal level at the reciever input, and that is all; you calibrate it with a signal generator. The S-Meter does NOT show real field strength at your QTH of the recieved signal, but the signal present at the reciever input, wich is a function of both antenna performance but also polarisation, impedance matching etc.
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TANAKASAN
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Posts: 933




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« Reply #37 on: September 09, 2012, 01:08:52 AM »

All agreed and we should know the standard already, -73 dBm or 50 uV = S9 Also, when we engage an attenuator or pre-amp inside the rig the reading should NOT change.

Tanakasan
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KK4IKO
Member

Posts: 67




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« Reply #38 on: October 18, 2012, 03:59:39 AM »

S-meter accuracy and speed?  It's all relative, and does it really matter one way or the other?  All I need to know is that the signal strength is sufficient to hear the other guy easily.  If he's over-modulating, you will politely let him know so he can change something.  The same applies if you can barely hear him, or you need to adjust something.  If an S-meter wasn't there, I wouldn't miss it.

I have one of those Nakamichi cassette decks.  Very fine equipment.  The VU meter is important for recording to get maximum strength and clarity without distortion, but that's all.  Using headphones for monitoring will tell you if there's significant distortion.

Bruce, KK4IKO
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WB2WIK
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Posts: 20633




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« Reply #39 on: October 18, 2012, 09:24:03 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.


Sure it is.  It's also less likely to fail or be damaged.  Cheap analog meters fail all the time.  Very good ones may not, but they're also expensive.
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