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Dual-mode, fluxgate-induction sensor for UXO detection and discrimination


We describe an innovative, dual-mode, fluxgate-induction sensor (FIS) that combines a DC magnetometer and an electromagnetic (EM) sensor. This sensor will enable one-pass unexploded ordnance (UXO) detection and discrimination using the joint measurements. The FIS is based on a 5-inch long, high-permeability magnetic core and a sensing coil that are shared by both EM and magnetic (MAG) modes. This integration makes the sensor very compact and removes the potential crosstalk problem of the core material of one sensor dominating the response of the other. A prototype receiver was developed and true serial, dual-mode operation demonstrated. The FIS achieved sensitivities of 1 nT rms in MAG mode and 0.2 pT/Hz at 1 kHz in EM mode, which compare favorably to existing commercial instruments. Triaxial dipole modeling confirms that three-component EM data are better for shape characterization than one (vertical) component. Assuming axisymmetry, inversions of three-component EM measurements of 22 cylindrical and disk-shaped targets yielded 100% correct classification of UXO-like objects (cylinders) and 38% misclassification of disks as cylinders. Degraded classification performance with increasing vertical distance may be caused by the small cross-sectional area of the FIS; an array will provide better field sampling. Triaxial dipole modeling of the MAG data confirmed its utility for detecting deeper targets using only the vertical component. Based on these results, the FIS is ready for field demonstration and validation.

ISSN: 1083-1363
EISSN: 1943-2658
Serial Title: Journal of Environmental & Engineering Geophysics
Serial Volume: 15
Serial Issue: 2
Title: Dual-mode, fluxgate-induction sensor for UXO detection and discrimination
Affiliation: QUASAR Federal Systems, San Diego, CA, United States
Pages: 51-64
Published: 201006
Text Language: English
Publisher: Environmental and Engineering Geophysical Society, Englewood, CO, United States
References: 13
Accession Number: 2010-066038
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Environmental & Engineering Geophysical Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201036
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