[Discuss-gnuradio] Maximum value of samples

[Sebastiaan Heunis]

Hi

Can anyone please suggest a setup that I can use to test the maximum
value of samples?  I know that we have 16bit signed values.  Looking
at the ADC interface on the USRP, we sign extend each 12-bit sample
and add 3 zeros to the right.  This should give us a maximum value of
16376 for samples?

I tried using a BasicRX daughterboard.  I have a function generator,
inputting a 20MHz, 10dBm signal into the db.  In my app I mix this
down to 100kHz using the cordic.  I also decimate by 16.  The PGA gain
is set to 20dB.  The FPGA build is the standard 2rx/2tx with hbf.  The
maximum sample value that I get with this is 8635, so I'm using about
half of the ADC's dynamic range.

Sebastiaan

-- 
Sebastiaan Heunis
Radar and Remote Sensing Group, University of Cape Town
Tel:  +27 83 305 5667