Accurate parameters estimation of chirp signal in low SNR

Aiming at solving the problem of great difficulty and low accuracy existing in parameters estimation of chirp signal in low SNR condition, an algorithm of accurate parameters estimation of chirp signal is proposed. Firstly, the algorithm extracts ridge frequency of chirp signal based on Short Time Fourier Transform (STFT). Secondly, the protruding glitch frequencies are eliminated through median filter with proper size and the smoothing frequencies are obtained corresponding to the time. Thirdly, the frequency-time FM (Frequency Modulated) line is fitted coarsely by the least-square linear fitting method, and some frequency points are removed, which are far away from the FM line. Repeat the process several times until the sample correlation coefficient of the fitted line is in high degree when the optimum chirp line is fitted out, so chirp rate and initial frequency are got. Monte Carlo simulation results show the effectiveness of the algorithm.