Magnetic screening system

Abstract

A magnetic screening system uses directional gradiometers with high resolution and accuracy to measure magnetic field signatures of target objects (e.g., gun, knife, cell phone, keys) in a volume of interest. The measured signatures can be compared to signatures of known objects stored in a local database. Various mathematical processes may be used to identify or classify target object signatures. In a network of magnetic screening systems, the magnetic screening systems can transmit signatures to a central signature database, and a management computer can share the central signature database with all of the magnetic screening systems on the network. The magnetic screening system can operate in multiple modes, such as a tracking mode, measurement mode, and self-test mode. Through use of unique processes and designs, the magnetic screening system can achieve a high rate of processing persons for target objects.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 11 / 073,424, filed Mar. 4, 2005. The entire teachings of the above application are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] In recent years, screening for weapons at entrances of public places, such as airports, governnent buildings, public schools, and amusement parks, has increased to ensure safety for the public at those places. Screening for weapons can include requiring people entering such public places to pass through a magnetic screening system such as a portal metal detector. Although people have become accustomed to passing through portal metal detectors, the process remains relatively slow for a number of reasons. [0003] One reason for the slow process is that people must empty their pockets of all metallic objects, remove their coats, and sometimes remove their shoes. The objects and clothing are either physically inspected by hand or passed throug...

AI Technical Summary

Benefits of technology

[0008] The principles of the present invention apply to multiple levels of a magnetic screening system and a network managing multiple magnetic screening systems. In a network embodiment, signature data (“signatures” or data) of target objects (e.g., guns, knives, cell phones, Personal Digital Assistants (PDA's), and other ferromagnetic materials) and information associated therewith can be added to and maintained in a central signature database. From this central signature database, a management computer can distribute the information and data in the central signature database to magnetic screening systems on the network for updating their local databases. As a result, the local databases can be continually updated, thereby allowing the magnetic screening systems to have knowledge of more target objects than if operating independently off the network for increased automation of detection, identification, or classification processes, among others, of target objects. Increased automation increases a rate of processing of people through the magnetic screening systems because operators of the magnetic screening systems have fewer incidents of having to manually inspect persons carrying target objects.

Problems solved by technology

Although people have become accustomed to passing through portal metal detectors, the process remains relatively slow for a number of reasons.

Another reason for the slow process is due to false detection or detection of non-weapon metals, such as wrist watches, belt buckles, metallic wires found in ordinary garments, personal adornments such as broaches or hair clips, and loose coins in pockets.

Typically, all of the delays result in a passthrough rate of between one and two hundred persons per hour.

To accommodate large crowds, many portal metal detectors are operated in parallel, which leads to staffing, training, and machine calibration issues.

When a person in a wheelchair passes through the portal metal detector, the portal metal detector is overwhelmed by the metal content of the wheelchair and unable to detect relatively small metal objects on the person.

In addition, even if the wheelchair is not passing through the portal metal detector, it can influence the detector to such an extent that the detector makes erroneous readings.

Active detectors can be dangerous for people using medical devices, such as pacemakers, that are sensitive to electromagnetic fields.

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