The Advanced Ordnance Locator (AOL): A Dual-Mode Tem and Magnetics System for Detection and Classification of Uxo

With funding from NAVEODTECH (Indian Head, MD), Blackhawk GeoServices is<br>collaborating with G&G Sciences and Geometrics to assemble and test a dual-mode system for ordnance<br>location combining a multi-sensor, multi-component TEM system with a total field magnetic<br>gradiometer. The new sensor array is integrated with an efficient computer-controlled transmitter and a<br>high-speed multi-channel (28-channel, 800 kilosample/sec) data acquisition system. The resulting<br>system has unprecedented capability and flexibility for the study, in particular, of the performance of<br>TEM systems and the noise that affects them. In this paper, we describe our dual-mode system and<br>present results from both local tests and tests at the Navy’s Baseline Ordnance Classification Test Site<br>at Blossom Point, MD. We compare data from our TEM system with the Naval Research Laboratory’s<br>man-portable MTADS and other systems as a baseline. Subsequent to our Blossom Point<br>demonstration, we experimented with alternative transmitter waveforms in an effort to improve the<br>signal to noise ratio (SNR) for detection. Our results demonstrate that the AOL system has a<br>significantly better SNR for detection during dynamic surveys than the other baseline systems with<br>which we compared. We attribute this improved performance to careful design of system components<br>together with an appropriate choice of the current waveform parameters (e.g., base period, pulse<br>polarity, etc) for dynamic data acquisition.