STFT is a simple and common method

STFT is a simple and common method for TFA of EEG, and it is based on a general sliding-window approach. The sliding-window approach assumes the non-stationary signal can be sliced into a number of short data segments, where the assumption of stationarity holds. In another word, although the signal has time-varying spectra, the spectrum of any one short data segment is fixed. Based on the idea of sliding window, conventional spectral estimation methods (such as the periodogram, the Welch’s method, the AR method) can be performed on each of these segments. Spectral estimates of all windows can then be concatenated to form a spectral power distribution in the joint time-frequency domain.