ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

4aUW13. Optimum wideband detection of solid spherical objects of uncertain composition in the vicinity of a smooth sandy bottom.

M. Wazenski

D. Alexandrou

L. W. Nolte

Dept. of Elec. Eng., Duke Univ., Box 90291, Durham, NC 27708-0291

Wideband detection of solid spherical elastic objects is approached via optimal detection and estimation theory in conjunction with acoustic scattering models for both the object and the seafloor. The objective is the time domain development of full field optimal decision methods for high-frequency active detection of a target in the vicinity of the seafloor. This parametric approach incorporates the inherent uncertainty surrounding the physical composition of both the object and seafloor. The acoustic model used for the spherical object is the well-known modal series solution and is parameterized by object size, density (object and medium), compressional wave speed (object and medium), and shear wave speed. This deterministic model is used to predict the target signature measured at an array of sensors. Acoustic modeling of the seafloor is performed through application of a modified point-scatterer model. This model provides a physical mechanism for describing the spectral scattering properties of the seafloor and is used to predict the spatial and temporal coherence of the scattered sound field. Illustrative detection examples are presented using both simulation and tank experimentation. Performance measurements are given by receiver operator characteristic (ROC) analysis. [Work supported by ONR: Ocean Acoustics.]