A robbery alarm is typically activated by an inconspicuous device such as a hold-up or panic button, a hidden foot rail or a device that is built into or attached to the item being taken. Most robbery alarms are silent at the location of the robbery and are audible/visible at an off-site location from which a response action is initiated. The holdup or panic button generates an alarm signal by hand activation of a hidden button, lever or similar device. Designed principally for robbery, this type of device is used also in situations that involve physical attack, violence, unauthorized entry, medical emergency and other situations that require immediate intervention. In some few cases, the alarm will activate at the place of the incident–the premise being that the robber or attacker will be frightened off.
The foot rail is a floor-mounted arched enclosure containing a switching device that operates when a person’s foot is slid along the floor under the arch to make contact with a pivoting bar. The rail is placed behind or under a disk so as not to be visible. The person assigned to activate the rail is typically a bank teller, store cashier, jewelry store attendant or other person having immediate access to the theft target. A variation is a button that can be depressed by the foot.
A third kind of robbery alarm activates when the theft target is removed such as when paper currency is slid from under a metal clip mounted inside a cash drawer. When the paper slides out, the metal clip comes in contact with a surface that causes activation of an alarm signal. Other variations include devices that detect movement of the theft target. A device can be a trip wire, electrically charged cable, capacitance switch, weight-pressure sensor or a device attached to or built into the theft target. Recent technology uses the Global Positioning System (GPS) to track movement and identify the location of the stolen item.
In addition to alarms that signal theft are identifiers that establish ownership of a stolen item and/or the place from which the item was taken. An identifier can be a unique chemical or metal compound or a signal-emitting component of an electronic product. The identifier bears a code, and it is inserted into the structure of the stolen item at the time of manufacture.