Blackfin real-time FFT

[bark]

Hello,

I have a Blackfin BF537 ez-kit for implementing FIR filters. At first I tried the BF specific FIR filter and

managed to run it real-time with 300 something taps. I then thought I might be able to improve this number by

doing an overlap-add/save(multiplication in freq domain) implementation with an FFT and it all works fine BUT I

can't run it real-time. I made a simple FFT->IFFT(without any filtering in between) and measured the time it takes as seen below.

(I did some testing in MATLAB with standard FIR and overlap-add method and the overlap-add really improved

performance even for smaller buffers.)

Im running the application as follows:

At a buffer size of 512 each iteration takes 17.45 ms. Changing the buffer size doesn't improve this. For a real

-time application this has to be done in about 10.7ms at a sampling frequency of 48kHz.

Am I doing something wrong or is it not possible to implement a real-time FFT @ 48kHz on a BF537?

If it is possible, how do I do it?

If anyone has any experience of this PLEASE let me know, Im in dire need of information regarding this!

/ Anders

Message Edited by bark on 05-31-2010 06:57 AM