The frequency axis for the PSD of a signal
3 views (last 30 days)
Show older comments
Suppose I have the signal x that contains N samples, and I take the FFT of this signal and rearrange the frequency components to have the 0 frequency componenet to the center
X = fftshift(fft(x));
and then calculate the PSD of the signal as
psd = (1/(fs*N))*abs(X).^2;
where fs is the sampling frequency, what is the exact frequency axis that corresponds to psd in this case? If I defined it as
freq = -fs/2:fs/N:fs/2;
it would be 1 element greater than the size of psd, but if I define it as
freq = -fs/2+fs/N:fs/N:fs/2;
it will be of the same size as psd.
Is the second definition accurate? If yes, why the negative frequencies don't extend to -fs/2 as it's the case for the positive frequencies?
Find more on Parametric Spectral Estimation in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!Start Hunting!