Abstract: Sound velocity profile represents the functional relationship between sound velocity and depth, which is often used in underwater acoustic location. The vertical axis represents the depth of the sea and the horizontal axis represents the speed of sound. In view of the contradiction between the positioning accuracy and the amount of calculation in the high-precision underwater acoustic positioning system, an adaptive layered algorithm of sound velocity profile is proposed. According to the characteristics of sound velocity changing in a limited range, the algorithm searches the sound velocity profile layer by layer. The gradient difference between sound velocity layers is used to represent the change of sound velocity, and the nodes of sound velocity change are found out. The original characteristics of sound velocity profile are retained to simplify the sound velocity profile. The simulation results show that according to the threshold value, the original sound velocity profile can be reduced by 70% after adaptive layered processing. Compared with D-P algorithm, smaller positioning error can be obtained when selecting the appropriate threshold. It has good engineering application value.

Key words: adaptive layering, gradient difference, sound speed profile, sound line tracking, underwater acoustic positioning