# Welch vs FFT squared in MATLAB [duplicate]

I'm trying to estimate PSD of a Binary signal with AWGN. Two inbuilt methods in MATLAB are giving me results one is Periodogram(Welch) and other is FFT squared. what is the basic difference between the two for giving me diffrent results? And which one is better please suggest.

• This is too broad. Both functions come with excellent documentation. Please state what of that you didn't understand. Hint: methods are almost never universally "better", unless you specify the specific measure for "good"ness. – Marcus Müller Dec 2 '19 at 11:58

Periodogram is an DTFT / FFT based nonparametric PSD estimator which is computed in Matlab/Octave by the following: $$\hat{S}[k] = \frac{1}{N} |X[k]|^2$$
Where $$L$$ is the length of the signal $$x[n]$$. It has got a number of options, including different windows, instead of a rectangular, to use.
Welch method is a variation of periodogram method in that it divides the signal $$x[n]$$ into smaller overlapping chunks, computes ordinary periodogram over those chuncks and then averages them to get the Welch estimate of PSD.