Alltem, A Triangle Wave On-Time Time-Domain System for Uxo Applications
David L. Wright, Craig W. Moulton, Theodore H. Asch, S. Raymond Hutton, Philip J. Brown, Misac N. Nabighian and Yaoguo Li
Event name: 18th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
Session: UXO Single Sensor Systems
Publication date: 03 April 2005
Info: Extended abstract, PDF ( 1.2Mb )
Data from tests of two electromagnetic prototype systems, the High Frequency Sounder (HFS),
and the Very Early Time Electromagnetic (VETEM) system at the Unexploded Ordnance (UXO)
Calibration Test Lanes at the Yuma Proving Ground, Arizona, showed good sensitivity to UXO objects,
but also considerable response to the electrical conductivity of the ground at frequencies above 20 kHz
or at the very early times provided by VETEM. To overcome these problems, we use a triangle wave
excitation similar to the one used by the UTEM system developed at the University of Toronto. One of
the favorable characteristics of such a system is that ferrous and non-ferrous metals behave quite
differently so that an operator can tell at a glance whether a response involves ferrous metals or not.
With such a system we can measure the transients to much later times than were possible with VETEM.
In addition, the ability to generate and measure three field components aids target discrimination and
identification. Results from laboratory test prototypes show good sensitivity to surrogate and actual
inert UXO items.