Measurement of underwater acoustic image positions using a horizontal linear array with focused beam-forming

A passive ranging method using focused beam-forming is proposed for near field,high accuracy ranging.According to the target's position in the measured field,the method applies spherical wave compensation to the received signal of every array unit to get the distribution of acoustic sources.To reduce calculation effort,the method first measures the bearing of the target using the middle array,then only scans the neighboring zone,a small angle around the target.Acoustic interference caused by the array pattern is inhibited by multi frequency band synthesis.This research suggests that the focused beam-forming method can produce two-dimensional acoustic images and high accuracy ranging for near field targets.