Anticipating environmentally related changes in the detection capability of exterior intrusion detection systems

Changes in detection capability due to winter and transitional environments have been determined for several exterior intrusion detection systems (IDS) for sensitive facilities such as nuclear facilities, by means of controlled intrusions and long-term monitoring of IDS performance. These changes have been evaluated in terms of environmental effects on the phenomenology by which each IDS detects an intruder. This paper summarizes the dependence of detection capability on operating environment. It identifies the site conditions (weather, snow cover, frozen/thawed state of the ground) that should be monitored in order to anticipate when and what changes in detection capability are occurring. Guided by an awareness of IDS performance as a function of the environment, security personnel may avoid vulnerabilities in detection capability by adjusting IDS sensitivity to maintain the required probability of detection without incurring unacceptable nuisance alarm rates