On Fri, Oct 07, 2005 at 11:44:27PM +0200, Stephane Fillod wrote: > > > > In the case of the 512kS/s to 48kS/s ddc, would the gr_rational_resampler > > > be able to replace gr_freq_xlating_fir_filter ? > > Ok no. > > IOW, the gr_rational_resampler does not do frequency translation, > and the USRP cannot decimate above 256. I used a decim rate > below 128 because I heard there's gain problems above.
Yes. If you need more decimation, just use gr.fir_filter_xxx. The first argument is the decimation factor. > So it looks like freq_xlating_fir_filter_ccf must be used. No, only if you want to decimate AND frequency translate. If you just want to decimate, use gr.fir_filter_xxx. If you just want to frequency translate, use a complex sinusoid LO and gr.multiply_cc. If you want both, use freq_xlating_fir_filter_ccf. > This is still ok, the whole ddc python script takes less than > 9% on a 1GHz AMD CPU. Still, I wished it would be less, because > I hope to eventually have several of them running in parallel, > plus a point and click waterfall, and some demodulating clients > around. > Patchs available on demand, comments welcome! Cool stuff. Looking forward to getting a chance to play with all of it. Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
