Abstract: A tilt compensated transducer array is provided with omni-directional transducers, compensated bi-directional transducers, and a processor which forms omni and bi-directional beams that are combined to cancel image lobes to give the array a uni-directional characteristic in which but a single, steerable main lobe is formed over a board range of steering angles. When the elements are located along a flexible line about which they naturally twist, a pair of orthogonally oriented bi-directional transducers is tilt or twist compensated to make image lobe cancellation possible. This is done by a compensator at each pair of bi-directional transducers which modifies their outputs in accordance with the deflection angle from the local vertical so as to obtain an output signal substantially the same as would be obtained by a single, properly oriented bi-directional transducer. Additionally, the use of a tilt compensated element permits discrimination of long range targets from short range targets.

Abstract: An acoustic line array which includes a co-axial cable having a center coctor surrounded by a flexible material of low-electrical conductivity. The flexible material is surrounded by a conducting material protected by an external shield. The cable has characteristic impedance which is sensitive to pressure variations in the medium due to a traveling acoustic pressure wave from an acoustic source. Variations in the impedance of the array are used to detect the acoustic source. Alternatively, the line array makes use of discrete sensors placed at suitable intervals along the array. This type of acoustic array eliminates the use of a plurality of wires carrying the electrical signals from the transducer to the storage equipment and elaborate multiplexing techniques.