Results from the Nantucket Sound autonomous underwater vehicle towed hydrophone array experiment

Results from several experiments with an autonomous underwater vehicle towed hydrophone array system demonstrate the ability of such a system to provide rapid, cost effective and accurate characterization of the shallow water waveguide. A synthetic aperture Hankel transform of the complex pressure as a function of range was used to estimate the eigenvalues and functions. Results showed that the vehicle was capable of towing the array in a steady and stable configuration sufficient for coherent processing and formation of a synthetic aperture Hankel transform. Transmission loss calculated with propagation codes that use depth and frequency dependent geo-acoustic profiles (compressional wave speed, density and attenuation) compared well with the measured transmission loss. The ability to perform coherent processing of the data obtained by this prototype system demonstrates that the system is an efficient and accurate alternative to traditional measurement techniques. Since the vehicle has the ability to change depth and course while measuring non-acoustic data such as currents, bathymetry, and sound speed; the time required for wide area characterization is significantly reduced