[Elecraft] signal strength

[Brian Lloyd]

There are really two problems here and they are not mutually exclusive  
so beating people up about how an s-meter should work is silly.

The idea that an s-unit is 6dB has been around only since Collins  
decreed it as such. Prior to that it was just an indication of AGC  
voltage at best. But the real definition of signal strength is a  
subjective one. The range (by ear) from S1 to S9 really spans only  
about 15dB-20dB of signal-to-noise ratio. By the time the signal is  
20dB out of the noise, it is S-9 by ear even though it only spans  
about 3 S-units from there down to where it disappears in the noise.  
So the s-unit as a measurement of absolute signal level is not all  
that useful.

The advent of DSP and SDR means that we can measure both signal  
strength and S:N very accurately even using a piece of amateur  
equipment, e.g. the K3. Personally I would rather dispense with S- 
units altogether and have a display of S:N and of absolute signal  
strength in dBm.

But that is the beauty of software: you don't need to change the  
hardware to add the feature.


Brian Lloyd
Granite Bay Montessori School          9330 Sierra College Bl
brian AT gbmontessori DOT com          Roseville, CA 95661
+1.916.367.2131 (voice)                +1.791.912.8170 (fax)

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