[600MRG] S meters and noise...

[Dave Riley]

Hi Ed, et al,

The numbers on the list are just cross references between dBm as in 
output of a signal generator or signal, microvolts on a 50 ohm line, and 
a receiver S meter, all relative to each other..

Spectra Vue for instants shows dBm down from 1 milliwatt= ZERO dBm, your 
signal generator referenced to dBm output, and a typical receiver 
calibrated to 50 microvolts @ S9

The next hurdle is to plant a decent antenna in a quiet location and 
find a way to wifi ( or facsimile ) for the back haul...

73s from DaveR/aa1a



On 1/18/2021 12:16 PM, Edward R Cole wrote:
> Dave,
>
> Interesting numbers.� With my 43 x 130 foot inverted-L and using a 
> SDR-IQ Rx I recall my receiver noise floor was -132 dBm.� With antenna 
> the local noise varied from -115 to -95 dBm.� WSPR improves SNR by use 
> of very narrow detection bandwidth in the Hz range (that reduces the 
> amount of noise energy vs signal).� My SDR-IQ running Spectravue 
> software displays in dBm so no s-meter.� My K3 is now upgraded to 
> operate on 470-KHz range so it has an s-meter (not in use on 630m as yet).
>
> 80m noise floor using an inverted-V runs S8 on the K3.� Hope that is 
> not indicative of what I should expect on 630m.
>
>