On Wed, Mar 14, 2007 at 07:31:33PM -0700, Chris Stankevitz wrote: > Hi, > > Should I get samples with a magnitude > 128 from the USRP no FPGA gain? > I believe the answer is no. Take a look at these plots of the data I > am getting (plot of real portion only): > > http://img157.imageshack.us/img157/8648/plot1gi6.gif > > http://img245.imageshack.us/img245/8528/plot2fp1.gif > > I collected the data using this method: > > ./usrp_rx_cfile.py -d 16 -f 1575420000 -g 0 -N 4000000 file.dat > > Furthermore, I created a test jig which wrote USRP output to stdout and > verified these spikes are not in the binary file or the binary file > reader. I'm using the DBSRX with a GPS antenna and a low noise amplifier. > > Thank you! > > Chris
Chris, Does it only occur once, and does it occur in the first 1024 samples? That is, if you look at, say 1M points, is there only a single occurrence? If yes to all 3 questions, then I think you're seeing a known problem where for some not fully understood reason (but probably related to failing to properly reinit the FX2 buffers and/or the FPGA) you get the sinc looking spike. Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
