S Meters

Simon Brown

Hi All,


Following Conrad’s thread I’ve updated Software Defined Radio (sdr-radio.com) so if there are any questions let me know and I’ll add more text or diagrams.


Simon Brown, G4ELI



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Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Hi Simon

Is it worth adding a small para about use of Visual Gain to calibrate the noise floor with no signal present (antenna disconnected) assuming that's a valid method, and so also therefore a mention of which radios have the Visual Gain feature?

Or perhaps just give Visual Gain it's own section with a link to it from the S-Meter section? It's just that Visual Gain is a very useful feature but it's true function seems to confuse some people quite a bit judging from the Forum posts.


Curt Faulk

Hi, Simon:

A typo crept in when we weren't looking...

And here's a Signal to Noise (SNR) meter. When observing what may appear to be just background noise you will typically see a level of ~8dB SNR. This is because the noise floor value is the mean (average) of the noise, but the noise itself will not be constant. If you don't belive this, just watch the S Meter of a traditional radio on what appears to be a quiet band.