The Detection and Discrimination of Small Munitions using Giant Magnetoresistive (OMR) Sensors

Abstract : This effort focused on characterizing the noise floor of giant magnetoresistive (GMR) sensors and evaluating their performance in detecting small (81 mm) munitions. A GMR sensor allows data acquisition over a broadband frequency spectrum in a single coverage, thus providing the capability of measuring responses presently requiring both a magnetometer and frequency domain or time domain electromagnetic induction sensor. Both the Honeywell and NVE GMR sensors studied have similar operating range, sensitivity, and noise levels. The additional features available on the Honeywell sensors make them the GMR sensors of choice. The performance characteristics of a single GMR sensor were studied, both as a static magnetic field sensor and time domain electromagnetic induction field sensor. In passive mode, the GMR sensor, which has a resolution of less than 10 nT, performed similarly to a cesium vapor magnetometer. When tested in dynamic mode for measuring the response of a single-turn copper coil, multi-turn copper coil, and solid copper sphere, the GMR sensor measured a distinct decay response for each target.