High-Resolution, Three-Dimensional Measurements of Low-Frequency Sound Propagation in Shallow Water
Final rept. 1 Mar 92-28 Feb 95
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF APPLIED OCEAN PHYSICS AND ENGINEERING
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An overview is presented of the Model Mapping Experiment MOMAX, in which both fixed and moving source configurations were used to transmit several pure tones in the frequency range 50 - 300 Hz in shallow water. The magnitudes and phases of these signals were recorded on several freely drifting buoys, each containing a hydrophone, GPS and acoustic navigation, and radio telemetry. High-resolution, three-dimensional measurements of the sound field were made out to ranges of 10 km and illustrate the influence of the laterally varying seabed in both the space and wavenumber domains. In addition, the phases of the measured signals show a remarkably high level of stability and regularity which can be exploited to make accurate estimates of the relative sourcereceiver speed from measurements of the time rate-of-change of the phase.