Stratification Effect Compensation for Improved Underwater Acoustic Ranging

Underwater acoustic localization usually relies on time of arrival (ToA) measurements, which are then converted into range estimates. However, the water medium is inhomogeneous and the sound speed varies depending on several parameters, e.g., the temperature, pressure and salinity. As a result, sound waves do not necessarily travel in straight lines. Ignoring this stratification effect could lead to considerable bias in the range estimates. We propose a depth-based approach to compensate the stratification effect for improved underwater ranging. We assume that the sound velocity profile (SVP) is only vertically stratified, the position of the sender is known, and the receiver has a noisy depth estimate via a depth sensor. We find a numerically simple range estimator, based on reconstructing the slanted path using Fermat's Principle and calculus of variations. This estimator removes the bias and is asymptotically efficient. We compare our solution to the simplistic linear estimator...

• Type: Journal
• Year: 2008
• Where: TSP
• Authors: Christian R. Berger, Shengli Zhou, Peter Willett, Lanbo Liu
• Keywords: Linear Estimator, Stratification Effect, TSP 2008, Underwater Acoustic Localization