I think that i am a little bit confused with
calibration. Is there any way to determine the gain of the
circuitry in front of the ADC? Is it correct enough to say that
power level at the input of PGA in front of ADC is
just ((sampled_value*Vp-p)/2^12 ^ 2 ) / Rinputpga?
The total gain in front of the ADC will vary from daughtercard to
daughtercard, and with frequency.
Calculate the power inside the flow-graph, which is proportional to
AVG(I*I + Q*Q). For RMS power, there's an RMS block.
What you need to do is use a *calibrated-in-power* signal source,
and use that to calibrate your receiving setup.
You can't reliably backtrack from the values coming out of the USRP,
because you don't know the total gain in front of the ADC to
sufficient
precision.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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