USA As Represented by Secretary of the Navy

Mary H Johnson

G Clifford Carter

David J Pistacchio

The invention as disclosed is a method for mitigating spatial aliasing that takes advantage of the forward motion of towed array elements to overcome the frequency constraints imposed on beam forming by the spatial separation of the array elements. The method employs the motion of a towed array of hydrophones to generate at least one synthetic array element to compensate for spatial under sampling.

Method for mitigating spatial aliasing

A system for close range sonar is provided. The system provides sufficient warning to permit maneuvering to avoid a close encounter even in the forward starboard/port regions, which have been problematic in the past due to ownship noise. The system utilizes a hull mounted sonar array and a towed sonar array which may be controlled in position to provide sufficient separation of noise received by both sonar arrays such that the noise is largely uncorrelated. The system utilizes beamformers for each array to supply a cross-correlator section which is able to minimize the ownship noise and maximize the signal thereby providing more time for maneuvering. The system also provides a LOFAR display and other displays that are highly sensitive to detecting close encounters.

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Middletown, RI, United States of America

Mary H Johnson