Abstract: Method and apparatus for localization and characterization of a magnetic rce including source strength and orientation. Samples of five tensor gradiometer signals from a straight-line track are used to construct a polynominial fit to each gradient tensor component with the variable being either time or track distance. Polynomial expressions are used to estimate rate of change of each gradient tensor component at the current sample, providing five numbers. Current samples of the gradient tensor components form a second five number set. An invention inversion process produces solutions for instantaneous bearing vector from the gradiometer to the source, direction in space of the source magnetic moment vector, and ratio of the magnetic moment vector magnitude to the fifth power of range from gradiometer to source from the gradient tensor component rate samples.

Abstract: A sensor for sensing the location of objects buried in the loose sediment in the bed of the sea. A hollow, cylindrically symmetric, conductive shell is used to inject current into seawater at its tips along its axis. A sensor coil oriented along the axis ignores all magnetic fields except those along the axis, and is used to measure return signals. This is particularly useful in detecting dielectric objects buried in the sediment and in rejecting motion relative to the seabed.