Help me understand my FFT output?

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C A
C A 2022-10-4
回答： Image Analyst 2022-10-4
I have two signals and I want to know if they have a natural oscillation. But I don't know if I mistook the signal noise for oscillations and decided to get the fast Fourier transform of my signals.
Here is what I see,
I am not sure what is going on with the green curve.
Here is my code:
plot(AgeBins1,Xidx2,'g','DisplayName','Signal 2','LineWidth',2);
Xidx2f = fft(Xidx2);
plot(AgeBins1,Xidx2f,'g','DisplayName','Signal 1','LineWidth',2);

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回答（1 个）

Image Analyst
Image Analyst 2022-10-4
Hard to say exactly but it looks like your green signal is sort of like a signal multiplied by a rectangular pulse or triangle wave. So the "true" signal will be convolved with something like a sinc function, which will give rise to the periodic ripples on your "true" signal.

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