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Author Topic: FFT on Arduino, the audio spectrum is cluttered?  (Read 5110 times)
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Shannon Member
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In theory there is no difference between theory and practice, however in practice there are many...
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@ aydingulgun
Please start your own thread and point to this thread (if needed), that way there is only one thread owner.


Rob Tillaart

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Don Bosley (b.1982) is an active composer, guitarist, and music technologist based in New York City.
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You should read the appendix of the "Computer Music Tutorial" by Curtis Roads or Appendix C of my master's thesis:

Despite some good information in here, there seems to be some broad misconceptions about what the FFT does, and what the resulting numbers actually mean.

Lacey, Washington, USA
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A word on lowpass filtering for Nyquist: Nyquist essentially says that you should have no (negligible) frequency content at or above 1/2 the sample frequency.

So if the sample frequency is 39ksps, you can't just use an 18.5kHz cutoff filter, because that is only -3dB down at the corner frequency of 18.5kHz, and lets through quite a bit above that.

You need a lower corner frequency and a high enough order filter to drop down the filter passthrough to probably -40dB at 1/2 of the sample rate.

Steve Greenfield AE7HD
CET Consumer Electronics and Computer
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