Underwater buried mine classifier

Claim 1

Apparatus for determining the magnetic moment of an underwater magnetic anomaly which may be buried in the bed of a body of water comprising: (A) an underwater platform including means for guiding said platform to a position above said anomoly; (B) a sensor system carried by said platform and including at least two vertically separated scalar magnetometers each operable to provide a respective output signal proportional to the magnitude of the magnetic field of said anomaly at the position of the magnetometer; (C) first means responsive to the outputs of said sensor system for obtaining an indication of the vertical spatial gradient of said magnetic field (dT/dz); (D) means for providing an indication of the vertical distance (Z) between said sensor system and said anomaly; (E) means for providing an indication of the dip angle (δ) of the earth's magnetic field at the location of said anomaly; (F) second means responsive to the outputs of said sensor system for obtaining indications of two orthogonal horizontal spatial gradients of said magnetic field (dT/dx and dT/dy); (G) third means responsive to said indications of vertical distance, dip angle, vertical and one horizontal spatial gradients for obtaining indications of the vertical and one of two orthogonal horizontal components of the magnetic moment of said anomaly; (H) fourth means responsive to said indications of vertical distance, dip angle, and the other one of said horizontal spatial gradients for obtaining an indication of the other horizontal component of the magnetic moment of said anomaly; and (I) means responsive to said vertical and horizontal magnetic moment components to obtain an indication of the magnitude of said magnetic moment.