Imaging of passive targets in shallow‐water using an ambient noise acoustic imaging system.

Abstract

This paper will describe an experiment on the detection of passive targets in shallow water using ambient noise as the sole source of insonification. Glegg and Olivieri [Noise‐Con 95, p. 1179] proposed a broadband signal processing technique to achieve this type of passive acoustic detection using a limited number of transducers. An array has been developed to apply this technique in a shallow‐water environment. This paper will describe an experiment carried out in Summer 1995 off the Boca Raton inlet in which a target was successfully detected. The size of the target chosen for this test was 1.8×1.2 m and it was placed 40 m from the array. The acoustic field was imaged with and without the target present and both passive and active detection of the target was obtained. The measurements were carried out in low sea states when the primary source of ambient noise was biological and strongly anisotropic. [Work supported by ONR.]