Model-Based UXO Classification Based On Static 3-Component TEM Measurements
Scott C. MacInnes*, Donald D. Snyder, David C. George, and Kenneth L. Zonge, Zonge Engineering and Research Organization, Tucson, Arizona
Paper – [pdf] UXO_Classification
An alternate method of characterizing an anomaly is to re-acquire it and to take more precise data by locating the antenna array at a few discrete stations in a pattern referenced to the center of the observed anomaly. In this paper, we describe experiments in UXO characterization using a multi-gate 3-component fast TEM (NanoTEM®) system. With this system, three orthogonal receiver antennas simultaneously acquire 31-gate TEM
Using this system, we have acquired data sets using two methodologies. In the first methodology, we take measurements with a 3-component cart system at 5 locations centered on the anomaly peak, thus acquiring 15 31-gate transients for use in the dipole inversion. In the second methodology, we use an array of flat-lying loops arranged to illuminate in 3 orthogonal directions and measure the target’s polarization response over a range of angles. Both data sets assure that the UXO has been polarized in its 3 principal directions. The dipole model simultaneously models both time and spatial components of the measured fields and reports a three-dimensional target position, spatial attitude, and polarizability parameters (i.e., the “beta” parameters) as a function of time. Results from characterization of various UXO and non-UXO targets models buried locally in Tucson and from the NRL Baseline Ordnance Classification Test site at Blossom Point will be used to illustrate the technique.