How to perform a zoom FFT on certain portion of a signal

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Austin Ukpebor 2021-1-23

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https://ww2.mathworks.cn/matlabcentral/answers/724977-how-to-perform-a-zoom-fft-on-certain-portion-of-a-signal

评论： Star Strider 2021-1-26

sensor4.csv

I have a signal with a sample rate of 200HZ, see attached. I am interested in a certain portion of the signal, so I zoomed in that section from the original signal (see figure below). I want to compute FFT (maybe zoom FFT) on that portion to see the frequencies within that region. Please I need help, thank you.

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Matt Gaidica 2021-1-25

@Star Strider has you covered on the FFT. I would offer that unless your hypothesis is that this phenomenon is rhythmic, an FFT may not be what you want. If your question is, rather, about how many times does my subject spawn over some amount of time, I think you would want to identify peaks in your data and come up with a mean rate (i.e. occurences / time). See also peakseek.

Austin Ukpebor 2021-1-26

Matt, your contributions on this platform and privately are a great deal to the success of my project. Thank you.

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Star Strider 2021-1-23

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First, see if the pspectrum funciton using the 'spectrogram' option will do what you want. It will segment the Fourier transform as a function of time as well as frequency. You can then easily see how the frequency content changes over time.

If that does not do what you want, please be a bit more specific.