Thanks Tom. if I really don't know how pfb_channelizer_ccf and pfb_decimator_ccf do, but they seem use the same principle. And how to set the taps?
On Thu, Dec 23, 2010 at 2:49 PM, Tom Rondeau <trondeau1...@gmail.com> wrote: > On Thu, Dec 23, 2010 at 1:19 AM, James Jordan > <james.jordan....@gmail.com> wrote: > > Hi Martin, > > pfb_channelizer_ccf will seperate all channels, But I dont need each > > channel. > > I only need the channel I am interested in. Seperating all channels will > eat > > a lot of CPU resource. > > > Not really. It's a very efficient algorithm and won't cost you that much. > > > > I have check pfb_channelizer_ccf source, it finally use fftw to process > > channelizer. > > So can I directly use fftw to do my work. > > Not quite. The PFB channelizer uses a filterbank where each filter is > specifically generated with a phase relation. The FFT part isn't doing > exactly what you expect it's doing. We'd have to go through the math, > though. > > If you are looking to just get a single channel out, then use the > pfb_decimator_ccf(N, taps, channel) to split the bandwidth into "N" > channels, using filter taps "taps," and you can specify which channel > you want to take by specifying the "channel." Here's the way to > translate the "channel" into the physical Nyquist zone you are looking > for N=7 (hopefully this format survives): > > Channel: 4 5 6 0 1 2 3 > Frequency: -3B | -2B | -1B | 0 | 2B | 2B | 3B > > Tom > > > > On Tue, Dec 21, 2010 at 6:19 PM, Martin Braun <martin.br...@kit.edu> > wrote: > >> > >> On Tue, Dec 21, 2010 at 06:02:44PM +0800, James Jordan wrote: > >> > Hi all, I need to receive many narrowband signals, but usrp hard ware > >> > only > >> > provide 4 RX, > >> > so I need to receive more than one narrowband signals per RX. Is my > idea > >> > possible? > >> > I dont want to use more than one usrp to achieve that, anyway which > will > >> > be an > >> > option if my first idea can't work. > >> > >> If your total bandwidth (sum of all bandwidths) does not exceed a couple > >> of MHz, you can use the polyphase channelizer (pfb_channelizer_ccf). > >> The result will be an equally spaced set of narrowband channels. > >> > >> Happy DSP'ing, > >> MB > >> > >> -- > >> Karlsruhe Institute of Technology (KIT) > >> Communications Engineering Lab (CEL) > >> > >> Dipl.-Ing. Martin Braun > >> Research Associate > >> > >> Kaiserstraße 12 > >> Building 05.01 > >> 76131 Karlsruhe > >> > >> Phone: +49 721 608-3790 > >> Fax: +49 721 608-6071 > >> www.cel.kit.edu > >> > >> KIT -- University of the State of Baden-Württemberg and > >> National Laboratory of the Helmholtz Association > >> > >> > >> _______________________________________________ > >> Discuss-gnuradio mailing list > >> Discuss-gnuradio@gnu.org > >> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >> > > > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > Discuss-gnuradio@gnu.org > > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > >
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