A Fast 4-D TEM System for UXO Characterization
Abstract
Electromagnetic induction (EMI) sensors are effective for the detection of unexploded ordnance (UXO) and other shallow-buried metallic objects because of their high electrical conductivity and magnetic permeability relative to that of the host medium. But neither frequency domain EM (FDEM) instruments that measure a single frequency nor time domain electromagnetic (EM) (TEM) instruments measuring the secondary EM transient over a single time window provide sufficient information to permit reliable classification or identification of target response. Consequently, during clearance operations, all metallic targets must be visually identified. Since each such target is potentially a piece of UXO, these targets must be identified by explosive ordnance disposal (EOD) specialists at an average cost that exceeds $100 per target. Current research in applying EMI to UXO detection is directed towards the development of new instruments and data processing techniques that promise to improve our ability to classify or otherwise identify a target as either UXO or clutter. In data processing and interpretation, research has been directed toward the development of physic-based models that help to classify targets according to shape characteristics extracted from the spatial behavior of the EMI response [3, 4]. Using a model based on a point dipole, these techniques have been shown to be effective in discriminating targets having UXO-like characteristics such as an axis of symmetry and aspect (i.e., a large length-to-diameter ratio). However, reliable model results can be obtained with this type of analysis only with a very high density of data points in the immediate vicinity of the target (usually within a radius of 1 m of the anomaly center). With conventional EMI instruments such as the EM-61, the required data density is obtained by surveying the area under investigation in two orthogonal directions at lane spacings of 0.5m. New instruments are being developed that sample the E
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2004
- Accession Number
- ADA607147
Entities
People
- D. D. Snyder