High Precision Algorithm For Underwater Multipath Channel Time Delay Estimation

The accuracy of underwater multipath channel delay is very important to the design of underwater acoustic communication equipment.However,it is difficult to meet the requirements of higher channel delay estimation because the delay resolution of traditional copy correlator is limited by the transmitted signal bandwidth.High precision underwater multipath channel time delay estimation is the main research content of this paper.Specifically,the high-resolution time delay estimation algorithm based on deconvolution is mainly studied.Furthermore,the non-sample-spaced multipath channel delay estimation algorithm under the condition of under sampling is studied,and the performance of the algorithm is verified by simulation and experimental data processing.Firstly,the underwater multipath channel model is established,and the propagation law of acoustic signal in the underwater multipath channel is discussed.Based on the model,the traditional copy correlator time delay estimation algorithm is deduced and simulated.The results show that the copy correlator can achieve multipath channel time delay estimation,but its delay resolution are not excellent.Secondly,three high-resolution deconvolution delay estimation algorithms,Richardson-Lucy algorithm,LS algorithm based on gradient projection method and FESCCO algorithm,are deduced and simulated under the condition of integer multiple sampling point channel,and the algorithm performance is analyzed in terms of precision and delay resolution.The results show that the delay resolution of the above three deconvolution algorithms is better than that of copy algorithm.Among them,RL algorithm and FESCCO algorithm have higher ability of sidelobe suppression.LS algorithm based on gradient projection method and FESCCO algorithm have better precision than copy correlator,while RL algorithm is less robust than copy correlator in low SNR.Finally,an improved FESCCO algorithm for non-sample-spaced multipath channel delay estimation is proposed under the condition of under sampling.Simulation results are given by combining RL algorithm and LS algorithm based on gradient projection method,and the precision and delay resolution of the algorithm are also analyzed.The results show that the improved FESCO algorithm can achieve non-sample-spaced multipath multipath channel delay estimation,and has optimal precision.The data processing results of pool experiment and lake test show that although the improved FESCCO algorithm and linear interpolation of LS algorithm based on gradient projection method have higher non-sample-spaced multipath multipath channel time delay estimation accuracy,their side lobe suppression ability is not as good as those biased algorithms such as RL algorithm and FESCCO algorithm.In conclusion,this paper studies the high-precision underwater multipath channel time delay estimation algorithm under the condition of known signal.The simulation and experimental data processing results show that the time delay resolution of the deconvolution time delay estimation algorithm studied in this paper is better than that of the copy correlator,and the improved FESCCO algorithm can effectively improve the accuracy of non-sample-spaced multipath channel time delay estimation.