IntelliFIBER/spl trade/ fence sensor installation on alternative fence constructions

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, IntelliFIBER/spl trade/, which uses fiber-optic detection cables and described its performance when installed on such a barrier type. We reported how this fiber sensor has a variety of cable and other options that allow it to be adapted to the specific site need. However, we note that different countries or types of sites may have predominantly other fence constructions than chain-link, to meet their specific appearance or threat level needs for a delay or sensing barrier. Hence it is useful to indicate specifically how this new sensor can be installed and function for applications on those 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 VIP residences and 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. One finds that these fences are used extensively in the UK in applications from tube stations to industrial campuses. Another fence construction consists of expanded metal panels, again used most extensively in European industrial sites but also in North America. With new terrorist threats of attack such fences may also have special constructions or modifications for high security, such as embedded vehicle anti-ram cables, or spiked toppings, which in turn require special sensor considerations. When deploying IntelliFIBER, as well as the fence type there are also 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 mounting, to calibration for different types of threats, to recording of performance. Actual test data from installations including our Sensor Integrated Test Environment (SITE) are reported, along with comparison data from chain-link fences in the same environment.