[hpsdr] Janus Lives!!

[Alberto I2PHD]

Robert McGwier wrote:
> 
> If this were calibrated and we saw -159 dBm in 500 Hz ( the meter is the 
> integrated noise power in the 500 Hz bandwidth in PowerSDR),   then at 1 
> Hz,   if we could do such a filter,  we would get approximately 26.9 dB 
> less power in the 1 Hz bandwidth  (  10* log_10(1/500)).   This is below 
> the theoretical noise floor since 1 Hz cannot be less than that for room 
> temperature since this is not in a system, it is the naked A/D.  It 
> cannot be calibrated.  Gerald is right.
> 
Bob,
    yes, you would be right if we were seeing -159 dBm in 500 Hz, which is not....
we are seeing -159 dBm in the bin size of the FFT, which Gerald in his second message said to be about 11.7 Hz
The -159 dBm are not what is reported by the meter, but what is visible on the spectrum display.

73  Alberto  I2PHD

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