Experimental Study of Acoustic Forward Scattering on a Marine Shelf

Abstract

The forward scattering of sound by a moving inhomogeneity can be observed when the inhomogeneity intersects a stationary path between an acoustic source and a receiving array. The scattered field is modeled as a weak perturbation of the direct signal when the inhomogeneity is near the direct path. Often the scattered field is masked by fluctuations in the direct signal. The task of a detection and parameter estimation of a moving inhomogeneity by the processing of acoustic signals as received on linear arrays is considered. After a review of methods, new experimental results are presented. The experiment was performed in the Bierke-Soond Strait of the Baltic in August 2006.The experiment geometry, propagation conditions, and spectra of direct signal fluctuations are discussed. Examples of experimental forward scattering observations obtained via various array-processing techniques are given. Good agreement between parameter estimates and true values is demonstrated for the intersection instant and the inhomgeneity's velocity, length and cross-sectional area. The minimum size of an inhomogeneity that can be observed is obtained.