I was able to run the following flowgraph: http://sbrac.org/files/multi_fft_graph.py
(GRC) http://sbrac.org/files/multi_fft.grc This runs at 4Msps complex, doing 131072-bin FFTs, giving a roughly 30Hz resolution in the FFT bins. The de-interleaver block "dispatches" out to 4 different FFT blocks, and I ran my tests on a *dual core* Pentium D 925 with 667-Mhz DDR2 memory. I used the default "TPB" scheduler. It handled the flow graph just fine without giving any USRP overruns, until I upped it to 8Msps, at which point, I was getting a lot of uOuO. This was part of the followup I promised to do a few days ago. My replacement mobo for my quad-core system arrives on Monday, so I'll re-try this experiment at higher bandwidths to see what happens. Unfortunately, I can't get FFT sizes greater than 131072, without provoking shmget() errors. This is actually a fairly encouraging result, assuming I didn't botch anything. I tested the results using my 21cm receiving setup, and my 21cm signal source, and things appear to be showing up correctly in the FFT outputs recorded in the output file. Cheers -- Marcus Leech Principal Investigator, Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
