Power Spectral Density Estimates Using FFT

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Yigao Shao
Yigao Shao 2015-5-21
回答： Jeremy 2015-6-18
http://www.mathworks.com/help/signal/ug/psd-estimate-using-fft.html
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 2015-6-18
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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