I sample an signal with around 840k values a second, to check the spectrum around <400kHz. But i can't save the whole data as it is just to much for my microcontroller. I know that for the butterfly-calculation you need values from begining and the end.
So is the whole set of data realy needed to calculate the fourier transform or is there some other way? And how long does it take to be able to process the newest samples of data.

  • $\begingroup$ what are you checking for? most people would break up their data in blocks a do an fft on each block. your question is too broad to answer with any confidence $\endgroup$ – Stanley Pawlukiewicz Aug 12 at 13:51
  • $\begingroup$ what's your expected spectral resolution and how wildy is your signal content changing ? $\endgroup$ – Fat32 Aug 12 at 13:52
  • $\begingroup$ i basicly have a resonant circuit which resonants with a certain frequency (as an example 100kHz). I try to specify my question: I want to check at which frequency the resonant circuit resonates. I want to detected changes as fast as i can. @StanleyPawlukiewicz can i just check a block at a time, say 2^8 data points? I thought because of the butterfly part of the calculation that i needed the full data (to detect up to 400kHz would mean i would need to process 800k samples). $\endgroup$ – Koen Aug 12 at 15:48
  • $\begingroup$ @Koen some 2^n would indeed work. you will probably need to do some trial and error to tune for your anticipated Q and latency $\endgroup$ – Stanley Pawlukiewicz Aug 12 at 15:55

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