The Impact of Constructing Sound Velocity Profiles Through Different Pressure-depth Conversion Models on Underwater Positioning

High-precision underwater acoustic positioning requires high-precision sound speed profiles. Currently, the depth information in the sound velocity profile, measured by the sound velocity profiler and the temperature salt pressure instrument, is calculated using the pressure depth conversion function. In order to solve the problem of high-precision underwater target positioning requiring high-precision sound velocity profiles, this study investigated the impact of different pressure depth conversion models on underwater target localization. The pressure depth conversion model derived from the EOS-80 seawater state equation is commonly used, but it considers fewer influencing factors. The pressure depth conversion model derived from the TEOS-10 seawater state equation considers factors such as temperature, salinity, and pressure that affect pressure depth conversion, and the model has a more rigorous calculation method compared to the EOS-80 model. This study selected 10 sets of CTD data collected by Argo buoys worldwide, and used the sound velocity profiles constructed by the two pressure depth conversion models mentioned above for underwater target positioning. During the positioning process, constant gradient sound line tracking was used to calculate geometric distance. The results showed that the sound velocity profiles constructed by two pressure depth conversion models produced a maximum difference of 4.1 cm when used for underwater positioning. In high-precision underwater target positioning, a more rigorous TEOS-10 pressure depth conversion model should be used to construct sound velocity profiles.