GUP Guoqiang YANG Yixin SUN Chao

(College of Marine, Northwestern Polytechnical University, Xi'an 710072)

Received May 14, 2009

Revised Nov. 18, 2010

Abstract A method for time reversal focusing with variable depth and range based on mode extraction was proposed. First, the normal modes of acoustic propagation in the shallow water are extracted by modal decomposition from the probe signals received by a source receiver array. Furthermore, a diagonal matrix and a vector determined separately by the depth and the range of the probe source are extracted from the received acoustic field data. And time reversal focusing at different depths and ranges can be achieved by modulating the depth-dependent diagonal matrix and the range-dependent vector properly. Then the diagonal matrix and the vector are modulated separately according to the depth and the range of the expected focal location to construct a new acoustic field vector. When this new acoustic field vector is retransmitted by the source receiver array in time reversal order (or phase conjugation in frequency domain), focusing of the resulting acoustic field at the expected location rather than the origin of the probe source can be obtained. Numerical simulations in typical shallow water environment demonstrate the effectiveness of the proposed method.

PACS numbers:43.30,43.60