[Discuss-gnuradio] Channelizing

[Marcus D. Leech]

I'm working on a multi-channel radiometer, based on USRP2 with the
dual-DDC feature.

I'm trying to come up with channelizing structure that won't overwhelm
my CPU--I'm using
  a 6-core Phenom II 1055T, with 4GB of 1333MHz memory.

I need to be able to carve-off 4 channels, with widths between 100KHz 
and 500Khz, anywhere within
  25MHz of the center frequency.

I've tried a single 25MHz input channel, then carving it up with 4 FIR
filters.  That produces massive
  'O', no matter how sloppy I make the channel filters.

I've tried a pair of 12.5MHz channels (using the dual-DDC feature that's
relatively new). That produces
  massive 'O'.

Since ultimately, I'm mostly interesting in channel power estimates, I
might just FFT it, and pick off
  the bin(s) that correspond to my channels.

Is one or two polyphase filter banks going to be cheaper?  And how do I
compute the taps?  There
  doesn't appear to be a helper function for that in GRC :-(


-- 
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org