Is the periodogram squared-magnitude DFT or squared-average DFT? How is the periodogram defined? I have been searching the internet a lot, and I find two different definitions:


periodogram is the squared magnitude of the DFT
periodogram is the squared average of the DFT


which one is correct?
The periodogram is simply the squared magnitude of the DFT. Since the periodogram is a rather poor estimate of the power density spectrum of a random process there are methods which use averaging of periodograms to obtain better estimates of the power spectrum. Two such methods are Welch's method and Bartlett's method.