UXO detection and identification based on intrinsic target polarizabilities — A case history

Abstract

Electromagnetic induction data parameterized in time-dependent object intrinsic polarizabilities can discriminate unexploded ordnance (UXO) from false targets (scrap metal). Data from a cart-mounted system designed to discriminate UXO of [Formula: see text] in diameter are used. Discriminating UXO from irregular scrap metal is based on the principal dipole polarizabilities of a target. Nearly intact UXO displays a single major polarizability coincident with the long axis of the object and two equal, smaller transverse polarizabilities, whereas metal scraps have distinct polarizability signatures that rarely mimic those of elongated symmetric bodies. Based on a training data set of known targets, objects were identified by estimating the probability that an object is a single UXO. Our test survey took place on a military base where [Formula: see text] mortar shells and scrap metal were present. We detected and correctly discriminated all [Formula: see text] mortars, and in that process we added 7% and 17%, respectively, of dry holes (digging scrap) to the total number of excavations in two different survey modes. We also demonstrated a mode of operation that might be more cost effective than current practice.