Discrimination of buried exploded ordnance by inversion of electromagnetic data requires accurate sensor positioning. There are many contaminated areas were dense forest or significant topographic variation reduces accuracy or precludes use of standard geo-location methods, such as satellite-based Global Positioning System (GPS) and laser tracking systems (e.g., Robotic Total Station, RTS), as these rely on line of sight. We propose an alternative positioning system that is based on a beacon principle. The system was developed to survey with the Man-Portable Vector (MPV) EMI sensor. The magnetic moment of the MPV transmitter can be detected at a relatively large distance. The primary field is measured from a portable base station comprised of two vector receivers rigidly attached to either ends of a 1.5 meter horizontal boom. Control tests showed that relative location and orientation could be recovered with centimeter positional and one degree angular accuracy within a 3-4-meter range and 60-degree aperture (relative to boom transverse direction), which is more than sufficient to cover any UXO anomaly. This accuracy level satisfies commonly accepted positional requirement for discrimination. The beacon positioning system can facilitate classification of munitions in any man-trafficable area and was successfully deployed at a field demonstration.
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