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Sliding DFT

Question asked by sander on Oct 15, 2014
Latest reply on Oct 20, 2014 by Jithul_Janardhanan



I'm using an adsp-21479 with an adc which has a sample frequency of 6kHz.


I want to implement some sort of a "bandpass filter" which does the following:

1) compute fft every time a new sample arrives on a 1024 points buffer

2) window the fft output so that only the frequency band of interest is maintained. The rest of the frequencies will be set to 0.

3) computer inverse fft to obtain the bandpass filtered input signal again.


I've managed to implement this using the library functions twidfft, rfft and ifft and it worked fine except for the fact that it is far to slow.

To optimize the algorithm I now want to use a "sliding DFT" which only computes the frequency components of the last sample and therefore should be much faster.


Since I'm not very familiar with the SDFT algorithm, I was wondering if there are some library functions for it?

Has someone implemented this algorithm before? Could you provide me some example code?!


Kind regards,