Inversion of frequency domain data collected in a magnetic setting for the detection of UXO

Nicolas Lhomme; Leonard R. Pasion; Stephen D. Billings; Douglas W. Oldenburg

doi:10.1117/12.780153

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29 April 2008 Inversion of frequency domain data collected in a magnetic setting for the detection of UXO

Nicolas Lhomme, Leonard R. Pasion, Stephen D. Billings, Douglas W. Oldenburg

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Proceedings Volume 6953, Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XIII; 69531I (2008) https://doi.org/10.1117/12.780153
Event: SPIE Defense and Security Symposium, 2008, Orlando, Florida, United States

Abstract

Magnetic soils are a major source of false positives when searching for landmines or unexploded ordnance (UXO) with electromagnetic induction sensors. The viscosity effects of magnetic soil can be accurately modeled by assuming a ferrite relaxation with a log-uniform distribution of time constants. The frequency domain response of ferrite soils has a characteristic negative log-linear in-phase and constant quadrature component. After testing and validating that assumption, we process frequency domain electromagnetic data collected over UXO buried in a viscous remanent magnetic host. The first step is to estimate a spatially smooth background magnetic susceptibility model from the sensor. The response of the magnetically susceptibility background is then subtracted from the sensor data. The background removed data are then inverted to obtain estimates of the dipole polarization tensor. This technique is demonstrated for the discrimination of UXO with hand-held Geophex GEM3 data collected at a contaminated site near Denver, Colorado.

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Nicolas Lhomme, Leonard R. Pasion, Stephen D. Billings, and Douglas W. Oldenburg "Inversion of frequency domain data collected in a magnetic setting for the detection of UXO", Proc. SPIE 6953, Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XIII, 69531I (29 April 2008); https://doi.org/10.1117/12.780153

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