A method separating echo by adaptive chirplet signal decomposition based on FRFT

The movement of actual target is non-stationary, usually accompanied by rotation, swing and other non-rigid motion in the process of high speed flight. Adaptive joint time-frequency analysis is available to estimate target's motion characteristics. To solve the problem of complex of parameter estimation in the time-frequency signal decomposition, a method using adaptive chirplet signal decomposition based on fractional Fourier transform (FRFT) is proposed. First perform the estimated signal with consecutive FRFT, and search for local maximum. The fractional Fourier transform order number which corresponding the maximum is converted into the angle. Repeat this step, and calculating every energy focus point respectively in fractional Fourier domain, finally the adaptive chirplet signal decomposition is completed based on Chirp signal detection and parameter estimation in fractional Fourier domain. This method estimates a fewer number of parameters in signal decomposition, and has good noise immunity. The analysis of simulation proves the effectiveness of the method.