Modeling of high-frequency acoustic propagation in shallow water

Abstract : This research involves numerical modeling of acoustic signals through shallow water channels. The sound is computationally modeled in a vertical plane as a dense fan of beams radiating from the transmitter location. The cross section of each 2-dimensional beam is represented as a Gaussian distribution of acoustic energy. The Gaussian beam travels axially along rays governed by Snell's Law, dispersing in width as a function of travel distance. At arbitrary receiver locations in the planar sound field, the intensity of the propagated beams is integrated over time to synthesize the multipath channel response. The influence of the ocean channel is analyzed parametrically, including sensitivity of the eigenray structure and impulse response to water properties, channel boundaries, and source/receiver geometry. Specific maritime environments examined in this study are St. Andrew Bay, Panama City, FL, and Chesapeake Bay, Little Creek, VA. This research supports the possible use of high frequency acoustics (40-70 kHz) for short-range (500 m) through-water communications. Emphasis is on communications between seabed stations.