Traditional parameter estimation methods of multi-component linear frequency modulation (MLFM) signal based on Fractional Fourier transform (FRFT) could solve neither the satisfactory precision nor the lesser computation cost. A new method, Short time Fourier transform (STFT) and Zoom-FRFT combined, is proposed in this paper. Firstly, the short-time Fourier spectrum of MLFM signal is obtained by using STFT, and the parameters coarse estimation result from the straight line detection of short-time Fourier spectrum. Then, the analysis scope of transform order and Fractional domain spectrum are calculated with the Fractional domain spectrum distribution characteristics and the main lobe bandwidth of window. Finally, the optimal order and the precise peak position are estimated by using the optimum seeking method in the Zoom-FRFT domain. The simulation results show that, compared with the traditional method, the method can improve both the parameters estimation precision and the computation cost significantly, and can flexibly choose the width of window and the refining ratio.
