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Stand-Off Detection and Tracking of Concealed Weapons Using Magnetic Tensor Tracking, Final Activities Report

NCJ Number
Date Published
June 2001
20 pages
This final report discussed the potential for successful applications of passive magnetic detection technology alerting officers to the presence of a weapon prior to the exposure to danger.
With the vast majority of firearms and other weapons incorporating ferrous metals or ferrous steel alloys, the use of magnetic detection technology has a wide range of potential applications for law enforcement, corrections, and general security. Under funding from the National Institute of Justice (NIJ), Quantum Magnetics (QM) reviewed the possible application of passive magnetic detection to law enforcement by providing officers with information to alert him/her to the possible presence of a weapon mitigating the safety threat. An officer’s safety in remote traffic stops was described with the use of passive magnetic detection. The officer directs the vehicle occupant(s) to exit the vehicle, walk back towards the patrol car, and than walk past the front bumper of the patrol car. The magnetic sensor is mounted on or near the front bumper of the car and automatically detects whether the individual is carrying a weapon.and where the weapon is located. The use of the passive magnetic detection technology was viewed as a viable option. Accordingly, a three-phase program plan was embarked upon. The first phase sought to establish the technical feasibility of detecting and locating weapons, primarily firearms, using a single magnetic sensor. In Phase II, QM designed and developed a pre-prototype sensor system, using low-cost magnetic sensors. The Phase III plan was to render the pre-prototype into a prototype system suitable for deploying on patrol cars. Summaries and results of Phase I through III are discussed. Under this NIJ funded program, six major technical accomplishments were sited: (1) the first fabrication and demonstration of a working magnetic tensor gradiometer (MTG) using magnetoresistive (MR) sensor elements; (2) operation of MR sensors with noise floors below 1 nT/Hz1/2 at Hz; (3) successful operation of MTGs mounted on vehicles to detect magnetic targets; (4) development of a robust algorithm to locate magnetic targets; (5) development of a robust algorithm to compensate for the distorting effect of nearby, stationary ferrous structures; and (6) development of an adaptive filtering algorithm that suppressed patrol car interference by 20 dB. Under this program, the work performed was technically a success. However, the basic application scenario (remote traffic stops) proved unfeasible. The Fourth Amendment precludes an officer from requiring vehicle occupants to exit their vehicle without probable cause. The report expressed ongoing application in other scenarios for law enforcement, corrections, and general security. Graphs and diagrams

Date Published: June 1, 2001