Researches on 3D passive positioning in near field using focused beam forming

Focused beam forming is measurement technology with high precision. In this article, we put forward a 3D passive positioning method based on focused beam forming for the first time. Fixing a hydrophone array on the bottom of the sea, it received sound through multi-path channel from the target. Direct sound and first sea return formed two bright spots in the acoustic image measured by focused beam forming. From the coordination of the two bright spots and array elements, as well as the scanning depth, we calculated the position of the target. It also provides a method to track underwater moving targets. Simulation confirmed that the method could effectively and accurately accomplish the task of positioning and tracking.