Research on the direction estimation algorithm of vector hydrophones under near-field and Far-field Reflecting Boundary

To address the impact of reflection boundaries and port and starboard ambiguity on passive sonar positioning, a method of vector hydrophone hybrid source positioning under different reflection boundaries is proposed. When the reflection boundary is close to or located within the near-field Fresnel zone, the reflected waves will increase and decrease because of the superposition of the line-of-sight waves, thus affecting the positioning results. The composite vector hydrophone consists of three-dimensional orthogonal vector channels and scalar channels. By fully utilizing the vector information in the MUSIC algorithm array flow pattern, the ambiguity problem of the azimuth angles on both sides under far-field and near-field reflection boundary conditions can be solved. By establishing different reflection models, the array manifold matrix of the three-dimensional directional angle and distance of the sound source under dual reflection is derived to illustrate the influence of reflection boundaries on position estimation. Comparing the simulation results with Cramer Rao bound (CRB) and maximum likelihood estimation algorithms, it is proven that the proposed method is correct and efficient. Finally, the effectiveness of the method is verified through lake experiments. This study has important guiding significance for the practical promotion of underwater acoustic engineering.