NCJ Number
138412
Journal
Security Management Dated: (July 1992) Pages: 50-52,54
Date Published
1992
Length
4 pages
Annotation
The most effective combination of barrier and detection capability in a perimeter protection system usually consists of an appropriate fence coupled with one or more carefully selected intrusion detection sensors.
Abstract
These sensors are categorized as those that use the perimeter fence as a platform to support the detection device and those in which the sensor also acts as a fence. Strain-sensitive cable sensors "hear" the mechanical movement when an intruder attempts to cut, climb, or jack up a protected fence. They offer a high probability of detection and a low nuisance alarm rate. Mechanical fence disturbance sensors use a seismic mass, weight, or other inertia-based device to detect fence motion associated with an intrusion. Electromechanical fence disturbance sensors utilize piezoelectric crystal devices, mounted to the fence fabric or to the fence posts, to detect unusual movements. Electrical field and capacitance sensors create an invisible electric field; an intruder disturbing this field will activate an alarm. Taut wire sensors, which set off alarms when wires are cut or deflected, present a formidable appearance and have high deterrent value. There are two types of fiber-optic-based sensors available: microbending fiber-optic and breakwire fiber-optic fence sensors.