Abstract:

A shallow-water acoustics modal mapping experiment (MOMAX) was conducted in March 1997 in the vicinity of the East Coast STRATAFORM site. An acoustic modal field was established in a shallow-water environment using fixed and drifting sources radiating several pure tones in the range 50--300 Hz. The field was then densely sampled on a horizontal plane at midwater depth using freely drifting buoys equipped with suspended hydrophones and a radio telemetric link to the ship for data acquisition. GPS and acoustic navigation were used on each buoy for precise spatial tracking to a maximum range of 10 km. An overview of the experiment is presented emphasizing buoy configuration and drift paths, signal processing, and acoustic field mapping. Specific buoy deployments will be examined with regard to the lateral variability of the acoustic field using data obtained from the two-dimensional buoy drift tracks. [Work supported by ONR.]