ALLTEM FOR UXO APPLICATIONS – FIRST FIELD TESTS
David L. Wright, Craig W. Moulton, Theodore H. Asch, Philip J. Brown II and S. Raymond Hutton
Event name: 19th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
Publication date: 02 April 2006
Info: Extended abstract, PDF ( 4.23Mb )
The ALLTEM system is a multi-polarization electromagnetic induction (EMI) system that uses a continuous triangle-wave excitation to drive each of three orthogonal (Hx, Hy, and Hz axes) transmitting coils. Received data are recorded on multiple simultaneous receiver channels. Multi-polarization excitation and received target data have potential advantages for determining location and orientation, and for discriminating between unexploded ordnance (UXO) and non-UXO objects. Tests at the Denver Federal Center (DFC) showed high sensitivity to the conductive ground, but buried target signatures can be recognized in the data in real time from time decay shapes. Tests at the UXO Calibration Grid at the Yuma Proving Ground (YPG), Arizona, demonstrate good detection, orientation, and composition sensitivity to buried UXO and non-UXO targets, good system stability, and much less sensitivity to the ground than at Denver. Discrimination between ferrous and non-ferrous targets is particularly simple. Multiply polarized data and time constant extraction from the data provide additional target information.