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From: Afinko on 14 Jan 2010 04:40
Thank you Michael, Rune and Kevin,

to go more deeply about what is my goal:
Yes, I really need a 4096 points describing 500 Hz range, exactly at range
2.5 kHz - 3 kHz. 16 seconds of data is not a problem. I can do the
decimation to the approx. 4 kHz sample rate. Effectively means to compute
this spectrum with small computation power and small memory usage on DSP. I
do not want to compute the large FFT from 0 Hz to Fs/2 and then to take
just the part of interest.

I am looking for some "mathematical trick" about how to compute FFT only
for frequency range of interest. I do not know if something like this
exist, that is why I am asking on this forum.

Zero padding is not a solution, i need a real resolution, not just an
interpolation.

Even the way how to compute FFT from Fs/4 to Fs/2 would be very helpful
for me.

Thanks in advance.
Afi
From: Afinko on 14 Jan 2010 05:09
I found that "ZOOM FFT" is exactly what I was looking for.
http://www.dewtronics.com/tutorials/dspintro/advanced/files/zoomfft.pdf

Thanks,
Afi
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