Design of an electromagnetic imaging system for weapon detection based on GMR sensor arrays

Concealed weapon detection is one of the most challenging issues facing the security community. It has been shown that each weapon can have a unique fingerprint, which is a set of electromagnetic (EM) signals determined by its size, shape, and physical composition. Extracting the signature of each weapon is one of the major tasks in any detection system. This paper addresses the design of a detection system for the identification of conductive objects based on their response to EM fields. The system consists of commercial Walk-Through Metal Detector (WTMD) and a Giant Magneto-Resistive (GMR) sensor array has been designed and built. Also, this paper describes how to construct a two-dimensional image from the measured signals to be used for image processing purposes. The system validity is then checked based on two concepts: data validation and multiple object separation. Finally, initial experimental work on the automatic detection and classification of different metallic objects has been carried out. The promising results indicate the feasibility of using this EM imaging method to identify objects.