Effects of the propagation environment on coherence of underwater broadband acoustic signals

Acoustic and environmental measurements were performed in 550 m of water approximately 2500 m east of San Clemente Island, California over a four-day period in August 2002. Continuous wave and frequency modulated pulses with center frequencies of 20 kHz to 40 kHz were transmitted over a 700 m distance underwater. Four projectors were located between 10 m and 70 m deep, and five receivers were positioned between 45 m and 220 m deep. Data from an anemometer, wave rider buoy, acoustic Doppler current profiler and towed conductivity–temperature–depth array were recorded simultaneously over the test period to characterize the marine environment. The extensive set of environmental data provided a basis for boundary condition and water column characterization. These conditions were input into a propagation model to predict the acoustic signal structure and propagation behavior in the measured environment. Predictions of acoustic propagation parameters will be compared to results from on-site acoustic measurements. [Work supported by ONR under Award No. N00014-02-1-0156.]