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Instantaneous Frequency Estimation of HFM Signal Based on Interpolated STFRFT-Variable Weight Least Square Fitting

To solve the problem of instantaneous frequency estimation of hyperbolic frequency modulation (HFM) signal under low signal to noise ratio (SNR), a Rife interpolation short-time fractional Fourier transform (STFRFT)-variable weight least square fitting algorithm is proposed. In a certain range of curvature, the fractional Fourier transform (FRFT) is used to better the energy aggregation of the HFM signal. The Rife interpolation is used to improve the estimation accuracy of the instantaneous frequency of the HFM signal. The variable weight least square fitting is used to eliminate the influence of the Rife interpolation abnormal point on the instantaneous frequency estimation and the accuracy is further improved. Finally, the effectiveness of the algorithm is verified by Monte Carlo simulation. The simulation results show that the performance of the algorithm is better than the STFT method.