ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

4pUW13. Average acoustic field in shallow water I: Active sonar performance prediction.

Ji-Xun Zhou

Xue-Zhen Zhang

Peter H. Rogers

Gary W. Caille

School of Mech. Eng., Georgia Inst. of Technol., Atlanta, GA 30332

The seabed dominates the shallow-water acoustics problem, but bottom properties and bottom scattering mechanism are usually poorly known. Detailed interference patterns in shallow water are thus not always physically meaningful for engineering applications. A simple analytical expression averaged over frequency or space can sometimes give better insight into some physical problems. In this presentation, an average angular power spectrum method for calculating shallow-water sound propagation, reverberation, noise, and spatial coherence is briefly introduced. The method is based on normal-mode and ray-mode analogies and originally appeared in Chinese papers which are not available in English [Zhou, Acta Acoust. Sin. 5, 86--99 (1980); Acta Ocean. Sin. 1, 212--217 (1979)]. Taking active sonar performance prediction as an example, analytical expressions for range/depth dependences of the sound propagation, average reverberation intensity, and echo-reverberation ratio will be given for several typical cases, including Pekeris shallow water, wedged continental shelf, and negative gradient waveguide. [Work supported by ONR.]