[hpsdr] Meaning of ADC-L and ADC-R metering in PowerSDR

[Brian Lloyd]

Today I was using my ANAN-10 to get an idea of the total power coming in
from my Pixelsat loop. This is a broad-band untuned loop with a preamp,
good pretty much from DC to 30MHz. (Really it is useful from about 50kHz to
20MHz but it does have significant output above and below that range.) My
assumption was ADC-L and ADC-R represented the actual ADC values relative
to full-scale, based on the fact that PowerSDR labels the value in dBFS
(decibels relative to full-scale).

You can imagine my surprise when I discovered that this value changed as I
"tuned" the radio. (Yes I did check the attenuator and made sure it was set
to 0dB for these tests.) Now my supposition is that what ADC-L and ADC-R
are reporting are the values of the samples in a given RX "slice" rather
than the actual ADC values. If this is the case, perhaps a new label is in
order in PowerSDR? May I suggest, "Not Very Useful - L" and "Not Very
Useful - R". Or perhaps, "Slice - I" and "Slice - Q".

But a reading of how close the input is to saturating the ADC(s) would be
very useful.

-- 
Brian Lloyd, WB6RQN/J79BPL
706 Flightline Drive
Spring Branch, TX 78070
brian at lloyd.com
+1.916.877.5067
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