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

[Marcus D. Leech]

> 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