Intrusion detection and assessment systems are an integral part of any physical protection system. Detection and assessment provide a basis for the initiation of an effective security response. Intrusion detection systems (IDS) should be designed to facilitate the detection of attempted and actual unauthorised entry into designated areas and should complement the security response by providing the security force with prompt notification of the detected activity from which an assessment can be made, and a response initiated. The method(s) of detection and assessment selected for implementation should be robust and be capable of providing the highest level of protection for the specific application. In the design of the detection and assessment aspects of a physical protection system, various methodologies should be incorporated to provide a fully integrated detection capability. The integration of various detection and assessment methodologies not only contributes to a superior detection and assessment capability, but also provides multiple overlapping layers that support each other if one method fails.




Intrusion Detection Equipment:


Premise Control Unit

A premise control unit (PCU) is a device that receives changes of alarm status from sensors and transmits an alarm condition to the alarm monitoring station. The PCU also allows authorised personnel to change the alarm zone status of the alarm zone.


Fence Disturbance Sensors

A fence disturbance sensor is designed to be mounted on a chain-link fence to detect disturbances of the fence, such as the noises or motions generated when an intruder attempts to climb over or cut through the fence fabric.


A climber generates two types of disturbance while climbing the chain-link fabric: a slow, low-frequency motion of the fabric movement and a higher frequency, impulsive shock or noise caused by pieces of the fence striking or rubbing against each other. Cutting the fence fabric also generates an impulsive shock. Some types of fence disturbance sensors have dual processors so that they can distinguish between the slow,low-frequency motion of the fabric and the high-frequency shock noises.


When someone or something causes a significant disturbance to a fence, a switch will activate, or a signal will cross a threshold, which is considered to be an event.


Most fence disturbance sensors require a specified minimum number of events to occur within a specified time in order to generate an alarm condition. For example, a facility could specify that an event must be detected five times within half a minute before an alarm is reported.



The decision for these parameters should be driven by the threat, physical protection program goals and the physical characteristics of the fence (i.e., height and wire mesh size). A lower number of required events would increase the probability of detection but increase the nuisance alarm rate as well. Requiring a higher number of events to generate an alarm would cause the opposite (i.e., a lower probability of detection but improved (lower) nuisance alarm rate).


The actual number of events over a specific period of time required to cause an alarm at a particular facility is generally considered sensitive information since knowledge of these parameters would give an adversary the advantage needed to possibly defeat that system.