A Study On Inversion For Sound Speed Profile In Shallow Water

This dissertation studies the inversion of sound speed profile (SSP) in shallow water,including the effects of sediment parameters on the multi-path arrival structure,the algorithm of the SSP inversion using multi-path arrival time differences and the SSP inversion based on matched beam processing (MBP).1. The effects of sediment parameters on the multi-path structure in shallow water are investigated in detail. A method of dividing the multi-path arrival time differences into groups is presented. Theoretical analysis for the method is given. An assumption is verified that the multi-path arrival time differences calculated by ray model is almost the same as that by normal mode model if higher frequencies for the source are used (e.g.,frequencies range between 600Hz and 1600Hz). hi other words,the calculation of the multi-path arrival time differences by ray model is reliable.2. SSP inversion based on ray arrival time difference in shallow water is presented and related algorithms are developed. The feasibility and practicability of the algorithms are studied by using the experimental data in the East China Sea. The robustness and convergence of the algorithms are theoretically analyzed. The simulation and experimental results show that the algorithms are robust on the mismatch of system parameters and sediment parameters. It is concluded that the proposed approach for SSP inversion is ready for some primitive engineering applications.3. The SSP inversion algorithm based on MBP is investigated. The feasibility of this algorithm is verified by using the experimental data of the East China Sea. The mean error of SSP inversion by this algorithm is less than that by MFI when the sediment parameters is known a priori. The SSP inversion by this algorithm shows a better match to themeasured SSP in the step layer.