Long Range Localization Method for Underwater Sound Sources Based on Beamforming Technique

For calibrating the emission sound source level of mobile sound sources in open waters, the location of the sound source is usually determined using GPS, ultra-short baseline, or inertial navigation instruments. After calibration experiments, it's essential to calibrate the time axis of both sound source level data and positional measurement data. As sound pressure data and sound source location are often collected on different vessels, a time axis calibration of both sets of data is needed before processing. To simplify this calibration process, a method based on beamforming for precise long-distance measurement of underwater sound sources is proposed. This method uses the geometric relationship between the virtual source created by water surface reflections and the actual sound source position for long-distance precise measurement and derives a formula for distance calculation. The feasibility of the theory was verified through numerical simulations, and the impact of linear array design on this method was discussed. Further validation was conducted during lake tests, analyzing the influence of the experimental sound field on the positioning algorithm. Within 200 meters, the positioning difference between this method and GPS results was less than 1%, demonstrating its feasibility.