Online Calibration Method of Sonar Array Receiving Directivity Based on USBL

An on-line calibration method for receiving directivity of low-frequency sonar in open water is proposed. Ultra short baseline (USBL) positioning and coordinate transformation technology are used to solve the positioning and orientation problems in the calibration process, respectively. In order to improve the positioning accuracy, the array design is optimized by expanding the array element distance. Linear frequency modulation (LFM) pulse signal and pseudo-random coding pulse signal are selected, and pulse compression method and complex correlation method are used to improve the ranging accuracy and direction finding accuracy, respectively. Simulated sonar receiving array is designed and simulation and dynamic experiments are implemented at the frequency of 2kHz to 8kHz. The results show that the improved positioning method has higher positioning accuracy and stronger anti-interference ability, and the directivity angle error is within 5.24%.