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Proceedings Paper

Application of multi-frequency EMI measurements for mine detection and clutter discrimination
Author(s): Bill SanFilipo; I. J. Won; Mike Shipman; Haoping Huang; Steve Norton
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Paper Abstract

The intrinsic frequency dependence to electromagnetic induction (EMI) measurements of a metallic object depends on the size, shape, and metal type. This frequency dependence, referred to as the spectral response, can be exploited in identifying or classifying the object, as well as suppressing spurious EMI responses to geology. In order to acquire the necessary multi-frequency data, a sophisticated EMI sensor is needed. The GEM-3 utilizes a continuous wave frequency-domain mode in which a hybrid current waveform is digitally generated containing energy at typically ten logarithmically spaced frequencies from a few hundred Hertz up to 48 kHz. The concentric-coil configuration suppresses the primary field at the receiver coil using a dual transmitter coil scheme. A digital Fourier transform is performed on the receiver coil emf at the selected frequencies, providing inphase and quadrature measurements. The detection channel, selected from several options, combines the multi-frequency channels in a way that suppresses the response to magnetic soil and emphasizes metallic targets. Once a target is detected, the spectral character is compared to training data spectra stored in a library for the anticipated mines, and if the goodness-of-fit to the best matching library item is within a threshold, a mine is declared. The matching algorithm essentially compares the shape of the inphase and quadrature spectra, but modifications have been incorporated to account for amplitude reasonableness, to suppress noise induced from magnetic soil, and to allow for larger percentage errors for weak-response low-metal mines.

Paper Details

Date Published: 10 June 2005
PDF: 12 pages
Proc. SPIE 5794, Detection and Remediation Technologies for Mines and Minelike Targets X, (10 June 2005); doi: 10.1117/12.602473
Show Author Affiliations
Bill SanFilipo, Geophex, Ltd. (United States)
I. J. Won, Geophex, Ltd. (United States)
Mike Shipman, Geophex, Ltd. (United States)
Haoping Huang, Geophex, Ltd. (United States)
Steve Norton, Geophex, Ltd. (United States)

Published in SPIE Proceedings Vol. 5794:
Detection and Remediation Technologies for Mines and Minelike Targets X
Russell S. Harmon; J. Thomas Broach; John H. Holloway Jr., Editor(s)

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