Ray/Beam Tracing for Modeling the Effects of Ocean and Platform Dynamics

In recent years, there have been notable technical advances in modulation schemes for underwater acoustic communications, and inexpensive commercial modems are now readily available. This has generated a renewed interest in modeling the effects of the underwater sound channel on the transmission of a known time series. The previously developed Virtual Timeseries Experiment (VirTEX) algorithm addressed the need for such models. It utilizes a sequence of ray-tracing computations on temporal snapshots of the environment. This approach can handle practical environments with arbitrary source, receiver, or sea-surface motion. While VirTEX can model the transmission of a known time series to any desired accuracy, its utility is offset by the computational resources required. In this paper, we present two new algorithms for modeling the propagation of a known time series in a restricted class of time-varying environments. The first algorithm can address steady motion of the source and/or receiver. The second algorithm can address a moving sea surface that satisfies some simple constraints. While more restrictive and less accurate than VirTEX, these new algorithms are significantly faster and more efficient. This makes them much more attractive for applications involving the modeling of extensive “what-if” scenarios. The algorithms can be implemented in software by postprocessing of the output from popular ray-tracing computer programs.