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

[Marcus D. Leech]

> What sort of CPU are you using?
>
> --Colby
AMD Phenom II X6 1055T, with 6GB of 1333MT/s memory.   Rough ballpark
calculations show
  me that even a 4096-bin FFT shouldn't take more than about
0.45GFlop/sec at 25Msps, and the
  CPU is easily capable of at least 8GFlop/sec/core.  So I'm not sure
why it's baffing at 25Msps.

I've tried using both the on-mobo 1GiGE interface, and a PCI-resident
one.  Neither of those makes
 any difference to getting large numbers of 'O' at 25Msps.

If I decimate by 3 or more before the FFT (after vectorizing), I runs
OK, consuming about 40% of the
  total system CPU, and not producing any 'O'.  I could then,
theoretically, process the FFT output vector
  to extract only the magnitudes of the bins that correspond to my
channels of interest.  But
  decimating by 3 means that I'm losing sensitivity by a factor of
sqrt(3), which I'd rather not have
  to "swallow", the application is for radio astronomy, where
sensitivity is quite important.

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