Experimental Study of Acoustic Forward Scattering on a Marine Shelf

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 inhomgeneitypsilas velocity, length and cross-sectional area. The minimum size of an inhomogeneity that can be observed is obtained.