Security Metal Detectors

Glossary of Security Metal Detector Terms
The following are common terms associated with security checkpoint screening using metal detectors

Access Point	An entry or exit of a checkpoint screening area.
Alarm	An audio or visual signal emitted by a metal detector when it detects metal. In a security application, the source of the alarm must be determined before a patron is permitted to leave a checkpoint screening area.
Archway	A term often used to describe the frame of a walkthrough metal detector
Audio adjust	The control used to adjust the volume level of sounds emitted by a metal detector
Bar Graph	A series of lights that indicate metal detection activity
Calibration	An umbrella term that refers to setting up a detector's programmes to meet specific security needs.
Checkpoint	An area where security screening occurs.
Conductance	The ability of metal to conuct electrical currents (e.g eddy currents)
Conductor	An object (e.g, pistol, knife, coin, keyring, etc) through which electrical currents can pass. Both ferrous and non-ferrous metal objects are conductors.
Detection pattern	A pattern within an electromagnetic field matrix. In the case of a walkthrough detector, the pattern forms along the vertical axis of the side panels, balloons outwards and evantually tapers off. The size of the pattern varies depending on the geometries of the transmitter and receiver coils; the type and strength of the transmission signals; and the size and nature of the metal item.
Earplug	An optional accessory used in conjunction with hand-held detectors to monitor alarms privately
Eddy currents	Also known as Foucalt currents. The primary electrical phenomenon responsible for producing detection signals. The detector's electromagnetic field generates eddy currents that flow throughout the surface of a metal object. Eddy currents use up electromagnetic field energy - resulting in a power loss that is sensed by the detector and reported via an audio or visual alarm. The flow of eddy currents is proportional to radio frequency and the conductivity of the metal object.
Electromagnetic field	An invisible field, generated by the alternating radio frequency cueent surrounding the transmitter coil, which radiates into the surrounding environment, be it rock, ground, air, water etc. The presence of a metal object results in a disturbance of the electromagnetic field, which is then measured by the detector and reported via an audio or visual alarm.
Electromagnetic induction	Current induced in a coil (or conductive object) due to changes in the electromagnetic field passing through the coil or object.
False alarm	A term used to describe an audible or visual detection response from harmless metallic items, such as jewellery or keys. Also referred to as an Explainable alarm.
Forbidden items	Items, such as guns and other contraband, which are prohibited from passing through a checkpoint screening area.
Hand held detector	A type of detector used for body searches, which requires no physical contact. Also known as a body scanner.
Hand carried items	Items such as hand-bags, luggage, back-packs, briefcases, cameras etc, which must be inspected visually and/or manually. Walk-through and hand-held detectors are not recommended for security inspection of hand carried items.
Induced current	A current flowing into a conductor during the presence of an electromagnetic field. With the exception of eddy currents, induced or secondary currents flow only where there is a complete circuit or closed loop. (Eddy currents themselves are closed loops).
Infrared analysis (IR analysis)	A type of sensor enabling the detector to ignore environmental interference while it detects metal. The infrared analysis renders the detector inoperable when the archway is empty, thereby reducing the likelihood of nuisance alarms. The sensor also helps generate a traffic count , keeping track of the number of people who pass through the archway
Interference reduction switch	A switch used to reduce the detection sensitivity of the Garrett Superscanner thereby lessening the likelihood of outside interference from nearby metal such as flooring rebar
LCD	A liquid crystal display that visually reports the calibration and operational information of a walk-through metal detector.
Magnetometer	An instrument that measures magnetic intensity, especially that of the earth. It is typically used to locate ferrous materials , particularly iron. A magnetometer does NOT directly detect the presence of metal. (See Metal Detector).
Manual inspection	The inspection method required for all hand carried items prior to their admission into a screened area.
Matrix	A matrix by defenition is something within which something else originates. In the case of a walk-through detector , it is the area within the archway which is "illuminated"by the transmission of an electromagnetic field.
Microprocessor	An integrated circuit comprising the necessary components of a small digital computer. A microprocessor enables the detector to perform numerous functions automatically instead of manually.
Nuisance alarm	A detector alarm triggered by interference from nearby metal objects or from electrical or mechanical environmental noise due to large motors, computers, video monitors, fluorescent lighting etc. The Garrett Magnascanner's infrared analysis helps reduce the occurance of such alarms.
Pack mule	A person recruited as a proxy to smuggle forbidden items through a security checkpoint screening system.
Penetration	The ability of a detector to "see through" a variety of materials, such as air, skin, wood, rock, water etc. in order to locate metal items.
Performance	The ability of a detector to perform the functions as specified by the manufacturer.
Pulse induction	The process of a current passing through a transmitter antenna coil intermittently. During the passive period, the antenna senses a secondary electromagnetic field caused by the presence of a conductor. Garrett's Magnascanner walkthroughs feature pulse induction circuitry.
Receiver coil	That part of a metal detector, which receives, processes and acts upon information generated by the presence of metal according to factory preset or manual calibration.
Random screening	A screening method in which people are randomly chosen to undergo inspection for forbidden items.
Scanning	A term used when describing inspections with a hand-held metal detector.
Screening	A security checkpoint system deploying metal detectors and manual inspection techniques to safeguard an environment.
Screened area	An area protected by security checkpoint screening. Only persons who have undergone a thorough security inspection are permitted inside this area. Also referred to as a sterile or secured area.
Sensitivity	The ability of a metal detector to respond accordingly to the size, shape, material composition and location of a metal object within the detector's electromagnetic field. Increasing or decreasing the sensitivity setting alters the degree of the detection response.
Sensitivity controls	A control used to regulate the sensitivity of the detector. The sensitivity level is typically set to a level that is high enough to detect the smallest forbidden object.
Signal	A general term that refers to the electromagnetic data received by the detector and the subsequent audio and/or visual response.
Stability	The ability of the detector's circuits to adhere to pre-determined operating designations. Stability is essential to any quality detector as instability can cause false alarms and detection errors.
Tamper alarm	A visual and/or audible alarm that activates upon any unauthorised attempt to alter a walk-through's control settings.
Transmitter coil	Wires bundled together to create a coil into which an electrical current is induced and an electromagnetic field results.
Unsecured area	The area located outside of any security checkpoint screening system.
Unexplainable alarm	An alarm whose source is unknown. An individual who triggers an unexplainable alarm is prohibited from entering the secured area until security personnel determine the cause of the alarm.
Uniform detection	A term used to describe the head-to-toe, uniform detection area within the archway of a walkthrough metal detector.
Visual indicator	A general term that refers to the alarm light, ready light, bar graph or POWER ON light of hand-held and walk-through metal detectors.
Volume control	A control used to limit the voltage and/or current inside an audio amplifier, thereby controlling the volume of a metal detector alarm.
Walk through metal detector	A metal detector resembling a door frame, which determines the presence of forbidden metal items on a person's body and/or in their clothing as they pass through the archway.

Visual Inspection

In addition to operating quality metal detection equipment, it is helpful for security personnel to sharpen their observational skills and familiarise themselves with physical and/or behavioural clues that may indicate that a person is hiding a weapon or other forbidden item on their person. The following are some common tell-tale signs to watch out for:

Attire
Unseasonal clothing. A person wearing an unusually heavy jacket in warm weather or wearing only one glove in cold weather may be trying to conceal forbidden items or to keep one hand free to grasp a weapon.

Heavy pockets. A droopy pocket that swings heavily as a person walks may contain a hidden weapon.

Unusual pocket protrusion or outline. The keen observer is always on the lookout for the outline of a gun or kinfe in a person's pocket.

Physical behaviour
Unusual stance, walk or limp. A person with no obvious injuries who has an unaturally rigid walk or an unusual limp may be concealing a weapon.

Unusually frequent clothing/pocket adjustments. A person will often touch or adjust a forbidden item such as a weapon, hidden in a waistband or pocket to prevent it from falling out, particularly when he or she stands up or climbs stairs.

Emotional behaviour
Unusual nervousness, discomfort or reactions.

Glossary of Security Metal Detector Terms

Visual Inspection