It's all about the Software

(reposted from IOGroups):

Does SDRC have a way to log average received channel power to file at
regular intervals? I was doing this with SDRuno & it works very well but as
I'm planning to move away from SDRPlay products I'll eventually need to use
something else. HDSDR can do it quite nicely but there appears to be a
rather large time constant (several seconds) applied to the S-meter.
Normally this would be a good thing, but since the power is only recorded at
0.1 dB resolution in HDSDR I prefer to apply less averaging to the recorded
data & do it myself in Excel so I can take advantage of noise dithering to
reduce the quantization error in the final power readings.

Simon: I saw your reply in IOGroups that said signal strength yes, power no. I don't quite understand: what would SDRC log if there was no signal? Peak power?

Bob NO6B

Bob,

Have a look - View.. Signal history. You can have up to 48 hours in the buffer and export to CSV.
Have a play, it may or may not be what you're looking for.

NO6B wrote: Thu Aug 20, 2020 8:04 pm (reposted from IOGroups):

Simon: I saw your reply in IOGroups that said signal strength yes, power no. I don't quite understand: what would SDRC log if there was no signal? Peak power?

Bob,

There's always a signal level, it's the peak value in the filter. As Jim suggests, see the Signal History.

Thanks. Signal history power values aren't affected by the RX IF bandwidth, so is it a recording of peak spectrum power at the RX frequency? At any rate, I think I do need total channel power, & I found that by switching the RX mode in HDSDR to LSB or USB the time constant on the RMS signal meter is greatly reduced so I can use that for now.

Bob NO6B

FWIW SDRC seems to be pretty accurate for relative readings. But it is not setup as an instrument to give you a reading that can be traced back to an actual power level. In the past I've found ways to completely screw up the NFM power readings with modulation designed to screw it up. So I trust it as far as generic relative power levels with some mental reservations.

{o.o}

The current application is noise figure measurement using a calibrated noise diode, first on the SDR directly then on an LNA connected to the SDR. I also use SDRs for radiometry, measuring absolute noise power. So although I can calibrate with the noise source, it would be better if the application recorded RMS channel power rather than peak power.