Chirp signal analysis based on PWD in fractional Fourier transform domain

A new pseudo Wigner distribution (PWD) in the fractional Fourier transform (FT) domain is proposed to analysis single or multi-component chirp signals. A rotated short-time Fourier transform (STFT) is used to realize the proposed distribution, and the appropriate fractional domain is found from the knowledge of second-order fractional FT moments. By analyzing the signal in the most appropriate fractional domain, the proposed time-frequency distribution preserves the WD auto-terms and cancels the cross-terms when there are several signal components. The proposed method is easy to be performed without the significant additional computational costs. Simulation results confirm a qualitative advantage in the time-frequency representation, when the calculation is done in the optimal fractional domain.