Time Delay Estimation Of Passive Sonar Signals

The study of time delay estimation of passive sonar signals has been the focus of the field of underwater acoustics.On the basis of summarizing the development history and current situation of time delay,this paper focuses on the accurate time delay estimation of passive sonar wideband signals and the delay estimation in multi-path environment.The basic theory of time delay estimation,including the performance evaluation criteria of time delay estimation and the time delay estimation method based on maximum likelihood criterion,is discussed.The mathematical model of time delay estimation is established.The accurate time delay estimation of wideband signals is studied.In order to solve the problem that the delay estimation accuracy of the related time delay estimation method is limited by the sampling rate,a fractional delay estimation algorithm is proposed,which can effectively interpolate the correlation peaks.The frequency domain zero-padding method is studied to improve the accuracy of time delay estimation.Aiming at the problem of large calculation of frequency domain zero-padding method,the correlation peak interpolation method based on improved Chirp-Z transform is studied,which reduces the amount of calculation.Combined with the limited frequency band of passive sonar signal,the spectrum of band-limited signal is studied.The refinement method further reduces the amount of calculation and improves the accuracy of delay estimation.The method of time delay estimation in multi-path environment is studied.The problems of related algorithms are analyzed.The MUSIC time delay estimation algorithm with high resolution is studied to realize the delay estimation and correlation peak resolution in multi-path environment.Aiming at the problem of large computational complexity of MUSIC delay estimation algorithm,a minimum variance time delay estimation algorithm is proposed.To solve the problem of unstable delay estimation in multi-path environment,the delay tracking algorithm is studied.The correlation peaks are tracked by its characteristics and stability.The algorithm improves the delay estimation performance in a multi-path environment.Simulation experiments verify the effectiveness of the above method.