Application of IntelliFIBER™ Fence Sensor To Different Fence Types

Perimeter intrusion detection systems using linear acoustic sensing cable are now widely used. Steel chain-link is one of the most common and inexpensive fence barrier materials, so is usually the medium on which these “microphonic” fence detection systems are mounted. In earlier papers we addressed a new sensor product, IntelliFIBERTM, which uses fiber-optic detection cables and we described its performance when installed on such a barrier type. However, we note that different types of sites, or countries, may use other fence constructions than chain-link, to meet their specific needs for appearance, or delay based on their threat scenario. Hence it is useful to indicate specifically how this new sensor can be installed and how it functions for applications on such barrier types. For example in many countries there are what are termed “ornamental iron” or ornamental metal fences, consisting of angular or tubular rails and posts. We find that these are used extensively in industrial site headquarters, due to their attractive appearance. There are also a variant of these fences termed “palisade” fences that generally consist of vertical or arched rolled steel pales. Another fence construction consists of expanded metal panels, again used most extensively in European industrial sites and more recently in North America. With new terrorist threats of attack such fences may also have special constructions or modifications for higher security, such as embedded vehicle anti-ram cables, or spiked toppings, which in turn require special sensor considerations. When deploying IntelliFIBER, when accounting for the fence type there are specific mounting considerations for the sensor cable. For example it must be simply and economically mounted so as not to be easily damaged, and must not detract from the fence aesthetics. This paper considers the method of application of fiber optic sensors to these alternative barrier types. It describes deployment steps from sensor mounting, to calibration for different types of threats, to recording of performance. Actual test data from installations including our Sensor Integrated Test Environment (S.I.T.E.) are reported, along with comparative data from chain-link fences in the same environment