By not using the built-in-to-grc LOG POWER FFT block, and careful selection of blocks, and eliminating blocks I didn't need (like the single-pole IIR filter), I was able to cut the virtual size of the process from over 7GB to 3.5GB. Still too large by (I think) a factor of two or more.
By hand-patching the grc_gnuradio/usrp library to load the 4rx_0tx FPGA file, I can do decim=4 with 8-bit samples, which allows me to squirt 16Msps over the USB. So, anyone want to buy me another 4GB of 667Mhz memory :-) :-) :-) There are some spectral "funnies" using this scheme, since there's no half-band filter, one has to rely on external filtering. The DBS_RX has a programmable low-pass on the I and Q baseband outputs, which I program with my usrp_ra_receiver code, but I have no way to do that within GRC, as far as I can tell. (Is there a way to put in arbitrary code blocks in GRC to do things like setup the low-pass filters on the DBS_RX????). -- Marcus Leech Principal Investigator, Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
