Re: [Discuss-gnuradio] Here's a little beauty

[Colby Boyer]

On Tue, Jul 5, 2011 at 6:58 PM, Marcus D. Leech <address@hidden> wrote:

Hi Marcus,

What are you using the vector sink for, I can't find anything that unloads it? If you look at the source code, this block continuously calls "push_back" on a STL vector container (element size is the GNURadio vector). So if nothing ever empties it, then it should consume all the memory space....?

--Colby

What I'm trying to do is do a cheap (in the computational sense) multi-channel power estimator, and I'm running out of options.
 I need to be able to carve out up to four variable-width, non-uniformly-spaced channels anywhere in the 20Mhz to 45Mhz region,
 which is 25Mhz of bandwidth.  I tried four conventional bandpass filters, followed by the usual power-detector sequence
 (complex-to-mag**2/IIR-filter/keep-one-in-n).  That produced a *lot* of overruns.  I then tried the same thing, using FFT filters instead
 of the usual FIR filters.  That was no better.

So then I thought, maybe an FFT of suitable size, and I can simply "pick off" the bins I need that correspond to my channels of interest.
 I could only make that work by decimating the FFT input vectors by a factor of 3, then integrating the outputs.  Similar to what the
 FFT graphical display does.  But, it does chug along producing those output vectors.  The question is, how to efficiently turn them into
 something I can use for per-channel power estimates, within the confines of a GRC-produced flow-graph.

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

Have you tried the polyphase filter channelizer blocks?

--Colby