A High Speed Towed Magnetic Array for In-Road Detection of Improvised Explosive Devices Employing Optimized Magnetic Map Differencing

Period of Performance: 12/11/2007 - 06/11/2008


Phase 1 SBIR

Recipient Firm

Geophex Ltd.
605 Mercury Street
Raleigh, NC 27603
Principal Investigator


This proposal describes an active electromagnetic induction (EMI) sensor array that can operate at a sampling rate of 750Hz, corresponding to 1.4 inches (3.5 cm) in distance at a moving speed of 60 mph. At low frequencies (below a few kHz), an EMI sensor is basically a magnetometer that responds to susceptibility targets (i.e., ferrous objects). The main difference is that, while a magnetometer uses the earth s field as the illuminating source, an EM sensor emits its own time-varying magnetic field and, thus, has the name electro-magnetometer. An electro-magnetometer acts like a magnetometer at low frequencies but also acts like a metal detector at higher frequencies, responding to conductive targets and, therefore, can also detect nonferrous objects (aluminum, copper, brass, etc.) that a magnetometer misses. The proposed electro-magnetometer will have a bandwidth of 750 Hz 96 kHz, for which it will behave like a magnetometer below a few kHz and a metal detector above. In this proposal, we describe our new electro-magnetometer technology that can meet all requirements for this topic: it will provide a high sampling rate (750 Hz), can have an arbitrarily wide swath, and can detect both ferrous and nonferrous targets down to 3 feet in depth for typical metal objects. The proposed sensor is based on successful commercial EMI sensors manufactured by Geophex for detecting and discriminating UXO/landmines. The primary difference will be the new high sampling rate to meet the requirements of this SBIR topic.