Angular propagation characteristics of surface waveguide leakage signal and its application to azimuth estimation

In the shadow zone of deep sea, the azimuth estimation based on the seafloor reflected rays suffers from significant errors due to the coupling effect between azimuth and grazing angle for a horizontal array. However, the presence of a surface waveguide in deep sea allows acoustic energy to propagate along the waveguide and leak into the shadow zone, providing an operational mode for sonar systems in the shadow zone. This paper uses the geometrical diffracted ray theory to present the angular propagation characteristics of the surface waveguide leakage signal (SWLS). Based on these characteristics, an azimuth estimation algorithm is proposed to accurately estimate the source azimuth. The propagation characteristics of the SWLS and the performance of the proposed azimuth estimation algorithm are validated through simulations and experimental data, with performance analysis conducted under various conditions. These results highlight the practical applicability of the proposed azimuth estimation algorithm in an ocean environment.