Passive synthetic aperture technique in adaptive beam space based on extended towed array measurements

Passive synthetic aperture sonar (PSAS), which uses the motion of the array to expand the virtual array to form a large aperture array, can significantly improve the azimuth resolution and weak target detection ability. The traditional (ETAM) can estimate the phase correction factor in the array domain, but its performance is poor at low signal-to-noise ratio. In this paper, adaptive beamforming and ETAM synthetic aperture methods are combined to estimate the phase correction factor in the subarray beam domain and perform adaptive beamforming. The results of simulation and experimental data processing show that the azimuth resolution and output signal to noise (SNR) ratio of the proposed method are 1.5° and 4.6 dB better than those of the traditional ETAM method respectively, and it is robust at low SNR, which provides strong support for passive weak target detection based on moving platforms.