Influence of the ray elevation angle on seafloor positioning precision in the context of acoustic ray tracing algorithm

Abstract

In high precision underwater acoustic positioning, the ray tracing algorithm is often used to reduce the acoustic ray error. However, it is generally assumed that precision of the acoustic ray with low elevation angle is the same to that with high elevation angle. In the context of the ray tracing algorithm, with the Snell acoustic equation we derive a relationship between the ray tracing error and the observational elevation angle, and then a stochastic model of acoustic positioning is established referring to this relation. Experimental results show that the acoustic observation noise level is highly related to the elevation angle. This indicates that, the weight of observation with low elevation angle should be reduced in the seafloor positioning, and the proposed model can be used to reduce the influence of low elevation angle observations on the positioning accuracy.