USA As Represented by Secretary of the Navy

Donald E Pugsley

John J Holmes

Robert W Schuler

Christopher I Conner

The present invention provides three different algorithms, namely, the 'divide and conquer' algorithm, the 'Hiddensee compensation' algorithm, and the &#x201c;impulse response&#x201d; algorithm. Any one of these three inventive algorithms may be made a part of an overall degaussing algorithm for a marine vessel. Each corrective algorithm, by itself, compensates for deviation of the vessel's induced signature from direct, linear proportionality to the ambient magnetic field. This deviation is associated with the dependency of a marine vessel's magnetic signature on the frequency at which the vessel rolls in the water. Practice of inventive compensation tends to be increasingly called for with increasing magnetic character of the vessel.

Roll frequency dependency correction to control magnetic ship signatures

Removal of extraneous magnetic measurement components from magnetic anomaly detection (MAD) tends to increase its accuracy. Conventional removal accounts for anomalous magnetism manifested by the MAD vehicle (typically, unmanned), but assumes that the magnetic field applied to the MAD vehicle is the earth's magnetic field, i.e., is non-anomalous and known. In contrast, the present invention accounts not only for anomalous magnetism manifested by the MAD vehicle, but also for anomalous magnetism manifested in the MAD vehicle's vicinity, such as by a manned control vehicle. The present invention's mathematical characterization of vehicular 'self-noise' due to induced and permanent magnetization is more refined, especially insofar as treating the vehicle's ambient magnetic field as an unknown (empirical) quantity, rather than a known (non-empirical) quantity. A typical inventive system for vehicular magnetic self-noise-reduced magnetic anomaly detection includes magnetic and other sensors, and a computer implementing the inventive mathematical characterization in processing the signals.

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Silver Spring, MD, United States of America

Donald E Pugsley