[hpsdr] PSDR stuff

[Warren C. Pratt]

If you mean, for example, looking at the dB reading of the noise on the 
S-meter at different bandwidths, you'll see a 3dB increase every time 
you double the receive bandwidth.  An S-unit is 6dB.  So, 1/2 half 
S-unit increase each time you double the bandwidth.  This is easiest to 
see in "Signal Avg" mode as the reading is more stable.

On the panadapter, you'll see a little less than 3dB change per doubling 
the bin-width.  This is due in part to the algorithm used to combine 
bins into pixels on the screen.

73,
Warren  NR0V

On 6/18/2015 5:00 PM, Hal Murray wrote:
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> "Warren C. Pratt" <warren at wpratt.com said:
>> S-meter:  Measures the noise within the receive bandpass.  So if, for
>> example, your receive bandpass is set to 3Khz, you are measuring the total
>> noise within that 3Khz.  Furthermore, you have your choice of measurement
>> modes for the S-meter - Peak mode (choose "Signal") or  Average mode (choose
>> "Sig Avg").
>> Panadapter:  Displays a set of narrow frequency bins across the screen.  In
>> Setup=>Display/... you can choose FFT size which changes the bin-width.
>> The noise within a very narrow bin is much less than the noise within the
>> entire receive bandpass which is displayed by the  S-meter.  There are also
>> various averaging modes that can be chosen for the panadapter.
> What happens if you plot things in dB/Hz?
>
>