> > In this example (and indeed, in the code for the analysis_filterbank), > we divide a 1MHz band exactly into 25 kHz channels. However, the > channels at the edge will be attenuated (cite: Matt's email of yesterday > 12:11 AM PST). I therefore oversampled the desired passband by 33%, > which causes the resulting wideband signal to not divide evenly into > channel-sized chunks. > > If I do some sort of 3/4 resampling should the passband quality suffer?
The simple way to think about this is that you have an RF bandwidth of the overall composite signal (let's say 4MHz), and you have the SPACING of each channel (not necessarily the bandwidth), say 25 kHz. So the math is --> 4Mhz/25kHz = 160. So you need a 160 point filterbank. It doesn't matter how many of those channels are occupied and oversampling is not an issue. It doesn't matter how wide the individual signals are either. In the case of the pagers, the signals are 16 kHz wide, but the spacing is 25kHz, and so we use 25 kHz channels. To be more specific, we are creating polyphase analysis and synthesis filterbanks based on the FFT. Matt _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio