Alltem, A Triangle Wave On-Time Time-Domain System for Uxo Applications

Data from tests of two electromagnetic prototype systems, the High Frequency Sounder (HFS),<br>and the Very Early Time Electromagnetic (VETEM) system at the Unexploded Ordnance (UXO)<br>Calibration Test Lanes at the Yuma Proving Ground, Arizona, showed good sensitivity to UXO objects,<br>but also considerable response to the electrical conductivity of the ground at frequencies above 20 kHz<br>or at the very early times provided by VETEM. To overcome these problems, we use a triangle wave<br>excitation similar to the one used by the UTEM system developed at the University of Toronto. One of<br>the favorable characteristics of such a system is that ferrous and non-ferrous metals behave quite<br>differently so that an operator can tell at a glance whether a response involves ferrous metals or not.<br>With such a system we can measure the transients to much later times than were possible with VETEM.<br>In addition, the ability to generate and measure three field components aids target discrimination and<br>identification. Results from laboratory test prototypes show good sensitivity to surrogate and actual<br>inert UXO items.