> On Thu, Dec 23, 2010 at 2:49 PM, Tom Rondeau <
address@hidden> wrote:
>>
>> On Thu, Dec 23, 2010 at 1:19 AM, James Jordan
>> <
address@hidden> 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 <
address@hidden>
>> > 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
>> >>
>> >>
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