A fast parameter estimation algorithm for LFM signal under low SNR based on FRFT

To estimate the parameters of Linear Frequency Modulated (LFM) signal based on Fractional Fourier transform (FRFT), the key issue is to determine the optimal order of FRFT. A new parameter estimation algorithm is proposed based on the idea of error iteration. The algorithm utilizes the conversion relationship between normalized bandwidth and rotation angle. Calculating the angle difference from the estimation error effectively reduces the amount of computation and does not require the prior information of positive and negative frequency modulation slope. The improved logarithmic search algorithm can further improve the stability and reliability of parameter estimation results. The simulation results show that the proposed method still has good parameter estimation performance under the premise of high efficiency when the signal-to-noise ratio is above -8 dB. The average estimation error is less than 1%, and the estimated results are close to the Cramer-Rao Lower Bound, meeting the requirements of engineering real-time processing.