We know FFT is not so best when the data is non-stationary like EEG. The FFT basis functions are global, hence they cannot treat local non-linearity without significant dispersion. But using HHT(Hilbert Haung Transform) we can get the Intrinsic Mode Functions(IMF) of Instantaneous frequency through Empirical Mode Decomposition(EMD). Is HHT the best way so far or is there any other way to do so?