THOMAS LEE SIWECKI
Pilots at Belleterre Dr, Danville, CA

4974213, Nov 27, 1990

Mar 20, 1989

7/326508

Thomas L. Siwecki - Danville CA

G01S 1500

367 88

A three-dimensional large scale rectilinear array of hydrophones comprising a plurality of equally spaced, fixed position, omni-directional, electro-acoustic transducers, utilizes aperture steering circuits to create a polar coordinate map indicating the bearing and elevation of incoming sound signals. The attitude and depth of the array is controlled by an array maneuvering system to position the array for maximum signal strength and to rotate the array to a horizontal position for maneuvering in shallow water. The geometric configuration combined with digital signal processing circuits provide improved sound detection threshold over linear and single planar arrays. An acoustically transparent housing is used to enclose the array. The shape of the housing and supporting structural frame are adapted to limit self-induced background noise. The hydrophones are also alternately connected to circuits for activating the hydrophone array to produce a low frequency (100 to 1000 Hz) frequency sound pulse defining a beam having a predetermined vertical and horizontal solid angle and predetermined bearing and azimuth.