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Power Spectral Density Estimates Using FFT

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Yigao Shao
Yigao Shao on 21 May 2015
Answered: Jeremy on 18 Jun 2015
In the code example, psdx = (1/(Fs*N)) * abs(xdft).^2;
why isn't it instead (Fs/N) such that psdx = (Fs/N) * abs(xdft).^2? Isn't the period equal to the length of the signal, which is N, multiplied by the sampling interval, which is 1/Fs ?

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Jeremy
Jeremy on 18 Jun 2015
There are different ways of looking at it but the PSD is often written as:
(fft*conj(fft))/(bin_width*NFFT^2)
(fft*conj(fft)) = abs(fft) and bin_width = Fs/NFFT, so you can see how it reduces down.

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