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Poster: Improved Methods for Detection and Classification of UXO Using Broadband Transient Electromagnetic Techniques

Publisher –
Zonge, 2004.

Authors –
Donald D. Snyder III, Snyder Geoscience, Inc.;
Scott C. MacInnes*, Kenneth L. Zonge, Jennifer L. Hare*, Zonge Engineering and Research Organization, Inc., Tucson, Arizona;
Mary M. Poulton, Department of Mining and Geological Engineering, University of Arizona, Tucson, Arizona

Poster Series – [pdf] TEMposterA   TEMposterB   TEMposterC
Panel A:   NanoTEM® – A System for Fast Multi-Channel TEM Data Acquisition
Panel B:   Static TEM Antenna Array; TEM Data Reduction and Parameterization
Panel C:   UXO Classification

Objective
Precision broadband electromagnetic induction (EMI) measurements can provide useful information for classifying buried metal objects such as UXO. But classification using EMI measurements is dependent on the precision of the position and orientation (i.e. heading, pitch, roll angles) of the antenna array and on the signal-to-noise (SNR) level of the observed data. These data attributes are degraded in dynamically acquired data. In this paper, we report on two projects funded by SERDP that investigate methods for improving classification and detection using the TEM method. The approaches under investigation are: 1. Increasing SNR with a High Powered TEM Transmitter and 2. Rapid Static Mode Data Acquisition for Queued Target Identification

High Power TEM Transmitter — Background

Since the late 1950′s, airborne TEM systems have been highly successful in finding mineral deposits and in mapping geology. These transmitters drive the transmitter loop with bipolar current pulses with a half sine wave shape. Conventional TEM systems transmit a series of long bipolar current

pulses. The abrupt termination of the current pulse (time rate-of-change of current) generates the EM induction.

Two current waveforms are illustrated below in Figure 1 (left panel). Most ground-based TEM systems use a transmitter waveform such as that shown in red; airborne TEM systems typically use a half-sine pulse waveform in order to generate the higher moments necessary for airborne operations (blue curve). These two current waveforms produce secondary transients with different characteristics. The time derivative of the current shown in the right panel of Figure 1, for example, drives induction EM. Equally important, however, is the fact that the peak transmitter moment (i.e., turns x Area x Current) for the half-sine waveform is usually much higher than the moments generated with conventional transmitter waveforms.

Can a TEM system driven by a half-sine pulse type transmitter improve UXO detection? With SERDP funding, Zonge Engineering is conducting research to determine the answer.