[600MRG] measuring noise level ?

[Glen Zook]

Actually, I have a number of "S" meters that are properly calibrated at S-9 = 50 microvolts and are pretty accurate above, and below, S-9.  However, I do agree that the majority of "S" meters, especially on "modern" transceivers, are not properly calibrated and are, in general, "very" generous!


I hear reports of 40 dB over S-9, and even 60 dB over S-9, being given on a regular basis.  The signal level required for a 40 dB over S-9 is 5,000 microvolts and for a 60 dB over S-9 is a whopping 50,000 microvolts when S-9 is 50 microvolts.  The Japanese manufacturers got into a "war" quite a while back with each claiming that "their" radios were more sensitive than those made by the other manufacturers.  However, basically, all that they did was to change the calibration of the "S" meter so that it read higher with a considerably lower signal level.  But, the average operator, these days, just accepts what the meter reads and, as such, gives out a higher reading than what a properly calibrated "S" meter reads.

 Glen, K9STH 
Website: http://k9sth.net

      From: Edward R Cole <kl7uw at acsalaska.net>
 To: 600mrg at w7ekb.com 
 Sent: Sunday, July 17, 2016 11:13 AM
 Subject: Re: [600MRG] measuring noise level ?
   
Most likely the poster of that noise measurement intended to say -85 
dBm.  Spectravue provides direct level measurements of signal and 
noise on a waterfall display.  Most SDR sw do this.

All modern service equipment show signal level in dBm.  I hear almost 
no one using uv anymore (unless they are audiophiles).  DBm are 
direct measurement in power while uv is ac voltage which requires one 
to specify the impedance if it is to relate to power.

So would you rather S-meter reading be given - ha ha!  Show me two 
receivers that have s-meter properly calibrated.