On 10/13/2011 09:11 PM, John Ackermann N8UR wrote:
Is there a (hopefully simple) example of using the polyphase
channelizer block in grc?
I'm trying to do a simple case of dividing a 250 kHz wide stream from
USRP into a small number (initially 4) of contiguous channels. Given
my generally ignorant status, I'm stumped on setting the parameters.
e.g. --
(a) is the "taps" param an integer or is it a firdes function as in
the xlating FIR filter?
(b) what is the oversample param used for?
(c) what is the sample rate of each of the output channels -- it
doesn't appear to be the same at the sample rate at the input, or
alternatively my parameters are so far off that what's coming out of
the thing is absolute junk (when I feed it into a USRP sink set to
250ksamples, I get screens of underruns).
Thanks,
John
If it's only 250Khz wide, and you only need four, have you tried 4
discrete freq-xlating FIR filters? They're fairly easy to use, and can
produce a baseband output at a decimated rate.
I haven't yet figured out how to use the polyphase channelizer because I
almost never have the N equi-spaced channels problem in
my fields of interest. So, discrete filters it is (sometimes a
hierarchy of discrete filters).
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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