USA As Represented by Secretary of the Navy

Peter T Shaw

Arthur P Stevens

Anthony Marino

The velocity of a vessel is determined in real time by a doppler sonar sym providing acoustic beams wherein received beams provide a plurality of bins or returns from various depth segments. The frequency shift with respect to at least two different bins is determined. The velocity of the vessel with respect to each bin is determined according to the phase shift of the respective bin. The vessel velocity is determined as an average of the determined velocities of the bins along the acoustic beam. The acoustic beams are paired to form beam pairs wherein each bin in one beam of the beam pair has a corresponding bin in the other beam of the beam pair. The phase shifts of the corresponding bins are used to determine a relative frequency shift for the corresponding bins. This determination is made along the length of the beams of the beam pair and averaged. The averaged resolved ship doppler profiler velocity when compared to inertial velocities determines water current velocities. When the bin averaged doppler velocities are compared to a sliding average of the water current velocities accurate reference velocities are output in real time for inertial navigation system velocity damping. In addition the real time depth change of a ship can be measured by integrating the summed vertical velocity.

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Warrington, PA, United States of America

Peter T Shaw