Year
2001
Abstract
Outdoor perimeter fence detection sensors must reliably detect intruders attempting to cut or climb a perimeter barrier fence. At the same time they must reject environmental noise, for example noise that is caused by the high electromagnetic fields at power generating stations. Many different detection principles have been employed over the years to provide a signature of an intruder. Many algorithms have been conceived to differentiate the characteristics of an intruder from those of a changing environment. This paper reviews the different technologies, and highlights how IntelliFIBERTM, a new fiber optic sensor provides improvements over other state of the art systems. Field test results are also presented, comparing IntelliFIBER with its triboelectric-based counterpart, Intelli-FLEXTM. Many different technologies are employed for perimeter detection, by constructing or sensitizing a barrier, including for example, strain-sensing taut wire sensors, electric fences, electrostatic “EField” sensors, and various linear “microphonic” cable-sensing devices. Their performance in terms of probability of detection, false and nuisance alarm rates, and vulnerability to defeat are discussed. The performance, installation and maintenance features of IntelliFIBER, a new fiber optic based product, are compared with these technologies. IntelliFIBER provides many advantages as an all dielectric cable sensor, such as simple installation on existing fences, resistance to electromagnetic interference and the ability to provide very long cable zones. As a system it is built upon the proven Intelli-FLEX platform, utilizing its processor with relay or bi-directional networked serial communications and its calibration module. This new product capitalizes on the Intelli-FLEX adaptive detection algorithms that have been developed through extensive field-testing to provide exceptional immunity to environmental alarms while still detecting the skilled intruder. There is an easy upgrade route for an existing Intelli-FLEX customer who may want the additional benefits of a non-conducting based sensing technology but wishes to retain their established calibration tools and processor interface. This can be accomplished simply by installing an add-on IntelliFIBER daughter card to their existing platform and adding a new fiber sensor cable to the fence. Also discussed in the paper are planned future developments of the product; including for example, new configurations with all-optical lead-in cables to further enhance field performance in harsh electromagnetic environments.