Time reversal focusing with variable depth and range based on modal extraction

A time reversal focusing with variable depth and range based on modal extraction is proposed. The normal modes of acoustic propagation in the shallow water are extracted by modal decomposition from the probe signals received by source receiver array (SRA). And a diagonal matrix and a vector determined separately by the depth and the range of the probe source are constructed from the received data. Time reversal focusing at different depths and ranges can be achieved by changing the diagonal matrix and the vector properly. Then the diagonal matrix and the vector are modulated according to the depth and range of the expected focusing position to construct a new acoustic field vector. When this new acoustic field vector is retransmitted by SRA in time reversal (phase conjugation), focusing of the resulting acoustic field at the expected location rather than probe source can be obtained. Numerical simulations in typical shallow water environment demonstrate the effectiveness of the proposed method.