A Large Incidence Angle Ray-Tracing Method for Underwater Acoustic Positioning

In the field of the precise underwater acoustics, the constant gradient ray-tracing method is the normal choice for positioning. But when the incidence angle is too large, the iteration of the incidence angle will diverge. In this paper, we analyze the reason behind this problem, and present a new iteration method for cases of large incidence angles. The key element of this method is to change the iteration parameter from the Snell refraction constant p to the radius of curvature R. We use simulation data to test the effectiveness of our method. The results show that when the incidence angle is not too large (e.g.≤80°), our new method and the original constant gradient ray-tracing method have the same accuracy, but when the incidence angle is large (e.g. >80°), the accuracy of our method is better than the original method.