Experimental validation of passive time-reversal and ray-tracing methods for underwater sound source localization

This study presents method for localization of an underwater sound source using a passive time-reversal method (TRM) in combination with a ray-tracing approach. For 2-D localization, sound signals from an underwater source are collected via a vertical array of four hydrophones. These signals are processed using the ray-tracing code BELLHOP to determine the acoustic pressure field of the time-reversed waves. The location of maximum pressure, based on TRM’s retrofocus characteristic, identifies the source’s range and depth. Validation experiments in a towing tank, along with field tests near Yanpu Harbor and Small Liuqiu Island, Taiwan, demonstrate that estimated positions closely match actual source locations. Furthermore, a cross-shaped hydrophone array is used to capture source signals. The source’s 2-D position is first determined from signals collected by the vertical hydrophones in the r-z plane, followed by calculating the pressure field from the horizontal hydrophones to find the 2-D position in the x-y plane, thus determining the source location at (x, y, z).