USA As Represented by Secretary of the Navy

Gerald T Stevens

Maurice J Griffin

Fred Nussbaum

An acoustic sensing countermeasure device is used to sense the direction of a threat projectile or vehicle in addition to countering the threat with noise or interference signals. Countermeasure device includes an acoustic receive array comprised of segmented vertical staves preferably mounted within a reduced diameter section around the outside housing of the countermeasure device. The staves are grouped to form directional acoustic beams across the entire horizontal plane. To determine the direction of the acoustic signals from the threat projectile or vehicle, the countermeasure device uses a method wherein the direction is indicated by the output of the directional acoustic beams. The countermeasure device locates a known reference direction used to determine the bearing of the threat. The bearing information can be transmitted, for example, to the vessel that deployed the countermeasure. In one example, the countermeasure includes a compass and the compass heading of North is used as the reference direction. Alternatively, countermeasure device can detect the vessel or another countermeasure device and use that as the reference direction.

Acoustic sensing countermeasure device and method of determining a threat direction

A sonar sensor array having a multi-layer tiling arrangement for the indiual elements that increases surface area available for each element while maintaining the inter-element spacing required to avoid spatial aliasing when the received signals are combined to form a sonar beam. The array comprises outer and inner arrays of transducer elements for converting an acoustic signal to an electrical response. The transducer elements of the outer array are positioned such than a grid of isolation spaces separates each of the transducer elements. The transducer elements of the inner array are also positioned such that a grid of isolation spaces separates each one of the transducer elements. The electrical response generated by the transducer elements of the inner and outer arrays are coupled to a beamformer which processes the responses to produce an output signal.

Multi-layer tiled array

A sonar array uses multiple acoustically transparent layers. One layer is a lanar array of acoustic sensors that is substantially acoustically transparent. Another layer is an acoustically transparent wiring assembly that provides electrical connection to each acoustic sensor. A third acoustically transparent layer is a planar array of signal processing circuits coupled to the wiring assembly for processing electrical signals generated by the acoustic sensors. Each signal processing circuit resides within an area that is in geometric correspondence with a respective one acoustic sensor. Each signal processing circuit can include a preamplifier, an analog-to-digital converter and a digital multiplexer.

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Portsmouth, RI, United States of America

Gerald T Stevens