Upward continuation of EMI data for sensing of subsurface UXO in cluttered, multi-object cases

摘要

In subsurface UXO sensing, single field (SF) data arises when an excitation field produces a single, spatially distributed response field that is sampled from a number of different locations. Measurements from traditional magnetometers furnish such data, for which the essentially invariant excitation is the earth's magnetic field. Upward continuation (UC) of SF data allows one to calculate signals that would be received at a higher elevation above the ground without actually raising the receiver. This is done without having to solve for the actual target characteristics or location. The technique is designed to smooth out the perturbations from irregularities and near-surface clutter. Applied recently to broader band electromagnetic induction (EMI) data of the the GAP SAM system, UC has shown distinct benefits in suppressing the strength of near surface clutter signals relative to those from a deeper UXO. Here we investigate possible application to the TEMTADS sensor. Preliminary results suggest that here too the method may bring out the signal of an underlying larger UXO relative to discrete clutter or smaller shallowers items, thereby aiding discrimination. In future work resolution issues must be addressed.