Optimal Depth-of-Field Selection Method for Large Aperture Sonar Focusing Beamforming Based on Image Sharpness Function

When the large aperture horizontal array is used for underwater acoustic passive positioning, focus beamforming is carried out. At this time, the depth of field is divided into several levels according to a certain gain attenuation coverage (such as 3dB), and these depths of field are processed simultaneously, so that the global target information can be quickly mastered. However, due to the gain loss, azimuth deviation and even split results of a certain range target in different depth of field processing, it is easy to cause false alarm or omission of the target, increasing the difficulty of detection. This paper proposes an optimal depth of field selection method based on sharpness function, which can obtain the optimal depth of field for single or multiple targets or moving targets, and effectively improve the detection ability and detection efficiency.