Abstract:
Concealed weapon detection is one of the greatest challenges faced by law enforcement community. Some kind of screening system is the need of hour to provide controlled access to the general public places. There is always a need of reliable and cost effective weapon detection system for terrorist groups and hijackers hiding different weapons. Current weapon detection systems mostly work on the principle of metal detection as harmful weapons are metallic in general. These metal detector gates work on the principle of induced magnetic field and Eddy currents and detect metallic objects observing the change in these magnetic parameters when metallic objects are placed in some magnetic field.
Cost effective weapon detection system based on inductive magnetic field technology has been developed. The technique is further classified into three categories depending upon the frequency of operation and the input source. Beat frequency method has been used in this project. A certain frequency is generated by a colpitt’s oscillator which is balanced by another oscillator. The search coil is the inductor used in the colpitt’s oscillator. When a metal is brought near to the search coil its inductance varies and the frequency of colpitt’s oscillator is changed. The difference of the frequencies is amplified and is used to trigger the buzzer. The gate has been divided into six zones to identify the exact location of the metallic object. Depending upon where the metallic object is detected and what is the strength of the signal at the output of the detector metal is classified to be of small, medium or large size using micro-controller.
