Computed time-reversing array retrofocusing in a dynamic shallow-water sound channel

Abstract

A time-reversing array (TRA) can retrofocus acoustic energy to the location of its original source even when the acoustic environment is complex and unknown. However, array performance is degraded when the acoustic environment is time dependent. Predictions of array retrofocusing performance require an acoustic propagation model for the environment. The model used in this study is a parabolic equation (PE) code (RAM by M. D. Collins). This study addresses the sensitivity of TRA retrofocusing to time variation in the water column of a shallow-water sound channel. These changes include internal waves and tidal fluctuations. Simulated variations are based on measured oceanic statistics. The influence of waveguide complexity on retrofocusing is also determined by adding range dependence and realistic bottom properties to the computational domain. Results are presented for a variety of ranges and acoustic frequencies. [Work supported by the Office of Naval Research, Ocean Acoustics.]