"westocl" <cweston_@hotmail.com> writes:
> [...]
> Im not sure what state of the art is.. but lets say i had maybe a power pc
> running at maybe 300 Mhz?? And i think would need a sample rate of maybe
> 100MHz.
>
> FFT size of ATLEAST 64. i would love to have 128.

According to the FFTW data here,

http://www.fftw.org/speed/G4-1.06GHz-macosx/

(I'm using single-precision, real-data, powers-of-two), you could
theoretically take a 128-point FFT of data at a sample rate of up to 188
MHz on a 1.06 GHz PowerPC using the VDSP library. (I used a mflops of
3300).

I didn't see any PowerPC slower than 1.06 GHz there.

I'm not sure if this is practically the case, e.g., you'd have to factor
in moving the data around, the OS overhead, and who-knows-what-else. And
that's just to get the FFT - what are you doing with the result?
Magnitudes? Youch!

Unless you've got a very unique scenario, this is the sort of thing
better-done in an FPGA, as others have already said.
--
Randy Yates % "And all that I can do
Digital Signal Labs % is say I'm sorry,
mailto://yates@ieee.org % that's the way it goes..."
http://www.digitalsignallabs.com % Getting To The Point', *Balance of Power*, ELO