Existing weapons detection systems utilize large fixed system (non-portable) x-ray style machines as found in airports. Public and private building entrances, mass transit systems and shopping malls currently employ few (if any) cost-effective means to perform mass screening for concealed weapons detection. Video surveillance has proven negligible as a deterrent, and in most cases only acts as a forensic tool for post event analysis.
Current technology principally employs magnetic fields and electronic processing to make an automatic yes/no decision on the possible presence of a weapon when a person enters a specially constructed portal. This equipment makes measurements over a wide band of frequencies. The parameters of transmitter pulse width, delay time, and receiver pulse width have been chosen to optimize the detection of handguns while minimizing the false alarm rate on innocuous metal. But many “false positives” occur and the system relies heavily on compliance by the subject. The system is not covert, expensive, slow and will not prevent a dedicated assault due to its fixed, highly visible location.