Portable Magnetic Gradiometer for Real-Time Localization and Classification of Unexploded Ordnance

We report progress toward achievement of a new magnetic tensor gradiometer technology that is being developed with support from the Strategic Environmental Research and Development Program (SERDP). The objective of this R & D effort is to provide a man-portable magnetic tensor gradiometer for real-time, point-by-point detection, localization and classification (DLC) of unexploded ordnance (UXO). The portable gradiometer processes data from triaxial fluxgate magnetometers to develop sets of rotationally invariant, "gradient-contraction-type" scalar parameters. The scalar parameters provide the basis for a unique Scalar Triangulation and Ranging (STAR) method that determines the UXO\´s position and magnetic signature. In particular, our paper presents: (a) A review of the magnetic STAR concept, (b) Details of construction and operation of the portable STAR-type gradiometer, (c) Results of computer simulations of the effects of fluxgate noise on the gradiometer\´s target-tracking performance and (d) Results of experimental measurements of uncorrelated fluxgate noise and correlated gradient channel imbalance errors, (e) Preliminary results from a gradient imbalance noise compensation algorithm. The R & D results indicate that the magnetic STAR concept potentially will provide an exceptionally valuable, motion-noise-resistant magnetic sensing technology for real-time, DLC of UXO, and buried mines