[600MRG] S meters and noise...

[Edward R Cole]

Dave,

OK, just a comparison chart.  Then you state S5 
(which converts to -97 dBm) is the noise level 
you hear with your antenna connected.  That is in 
the range I heard with my inverted-L to the SDR-IQ (-115 to -95 dBm).

The SDR-IQ is fairly accurate in signal level 
indications.  Noise is dependent on detection 
bandwidth.  Wide bandwidth => more noise.
I typically ran 20 or 30-KHz when I was watching 
for WD2XSH signals a few years ago.

I also use the SDR-IQ on the IF of my 1296-eme 
dish to measure sun-noise/cold sky noise.  I open 
bw to 190-KHz for doing that as I get a stronger noise signal.

GL with finding a quiet antenna location.  Wi-Fi 
should work if you have enough signal.  I hear of 
many ham stations running remote locations with internet control.

73, Ed - KL7UW (ex-WD2XSH/45)

At 11:03 AM 1/18/2021, Dave Riley via 600MRG wrote:
>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.
>>
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73, Ed - KL7UW
   http://www.kl7uw.com
Dubus-NA Business mail:
   dubususa at gmail.com