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Proceedings Paper

Transient electromagnetic responses during the transmitter on-time
Author(s): Gregory M. Schultz; Jonathan S. Miller; Lin-Ping Song; Leonard Pasion
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Paper Abstract

Current time-domain electromagnetic induction instruments generally only utilize data acquired after the cessation of the transmitted field. During this "off time", signals are dominated by induced eddy currents and magnetic surface modes, but do not fully capture the magnetostatic response of permeable and conductive metallic ordnance. In this paper, we investigate the response of EMI systems that measure signals during excitation of the primary magnetic field (the so-called "on-time"). Our analysis shows that on-time signals have great potential to yield useful information that is not often exploited in current EMI systems. We compare analytical models to data from state-of-the-art time-domain EM sensors that have the capability to sample receivers during the on-time. We present modeling results that represent the responses from different current ramps and on-time waveforms for objects and ground. We consider target and clutter objects and grounds having a range of material properties, shapes and sizes, and configurations and investigate signal processing and inversion methods for target detection and discrimination. Specifically, correlations between on-time and off-time signals are shown to be a powerful tool for discriminating ferrous and non-ferrous metallic objects.

Paper Details

Date Published: 29 April 2010
PDF: 11 pages
Proc. SPIE 7664, Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XV, 766405 (29 April 2010); doi: 10.1117/12.850510
Show Author Affiliations
Gregory M. Schultz, Sky Research, Inc. (United States)
Jonathan S. Miller, Sky Research, Inc. (United States)
Lin-Ping Song, The Univ. of British Columbia (Canada)
Leonard Pasion, Sky Research, Inc. (United States)
The Univ. of British Columbia (Canada)

Published in SPIE Proceedings Vol. 7664:
Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XV
Russell S. Harmon; John H. Holloway Jr.; J. Thomas Broach, Editor(s)

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