Simulative validations of RT2: A Real-Time Ray-Tracing technique for acoustic-based range evaluation

This paper presents simulations and a sensitivity analysis of a Real-Time Ray-Tracing (RT²) technique for acoustic-based range evaluation. The RT² is an algorithm that evaluates the range of an acoustic receiver from the emitter, while taking into account the anisotropy of the underwater medium, exploiting the knowledge of the depth information of both the emitter and the receiver, and the depth-dependent sound speed profile. This technique allows the vehicle itself to know its position, unlike COTS systems that are usually conceived for “tracking” the underwater devices. Moreover, the required hardware is only an acoustic modem, which is already necessary for communication, thus the algorithm can be easily implemented even on low-cost vehicles. The sensitivity analysis here presented shows that, even when the sound speed profile is not known exactly, the algorithm achieves a good precision when compared to straight ray propagation assumption, especially in the presence of the so called “acoustic channels”. Despite the presence of few outliers, and few limited zones when the algorithm performs worse than a straight ray assumption, in average the simulations shows an increase of one order of magnitude of precision.