Source localization in a deep ocean using the time difference of multipath arrivals

Bottom bounce is a typical sound propagation mode in deep oceans. A receiver moored below the sea surface receives sound waves transmitted from a submerged source through multipath paths. Four of them which traveled by bottom bounce mode play the leading role in source localization. A passive broadband source localization method is proposed herein based on the four arrival paths and using a single receiver. Through autocorrelation of the signal that is mainly composed of four multipath arrivals, six positive relative time differences that are dependent on the source range and depth are acquired via combination. The time differences are sorted in an ascending order to form a measured vector. A ray-tracing model is used to predict the replica vector. Then, the source is localized by fitting the replica vector to the measured one. An experiment is conducted in the South China Sea. The proposed method is utilized to successfully localize a source at a depth of 47 m below the surface and at a distance of 13.6 km.