signal strength

[Brian Lloyd-6]

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)

PGP key ID:          12095C52A32A1B6C
PGP key fingerprint: 3B1D BA11 4913 3254 B6E0  CC09 1209 5C52 A32A 1B6C




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[Julian, G4ILO]

Brian Lloyd-6 wrote

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

You don't even need to change the firmware. Just try a new program.

Folks who want to do comparative antenna tests should try WSPR by K1JT. It's a beacon software that also measures the SNR of other beacons received and reports them to a website (wsprnet.org.) Use it for a couple of hours and then go to the website and you'll have a bunch of reception reports from stations all over the world, with 1dB resolution, to compare with other antennas or the reports given to other stations in your locality. Much more useful than asking a QSO partner for an S meter reading if you ask me.