| Outdoor security sensors detect intruders as | | | | integrates and automates the control of the |
| soon as they enter a protected area and | | | | sensors and sensor alarms, significantly |
| before they can gain access to people or | | | | reducing the workload of the operator. These |
| valuable assets. | | | | systems can provide maintenance information |
| | | | to help diagnose problems with individual |
| In a correctional environment, security | | | | sensors and allow sensors to be adjusted from |
| sensors can be used to immediately detect | | | | the central control. |
| prison escape attempts. A quality outdoor | | | | |
| security system demonstrates a significant | | | | Outdoor sensor types: |
| return on investment by reducing the risk of | | | | |
| theft, damage or personal injury. | | | | Many types of outdoor sensors exist in the |
| | | | market. The most appropriate sensor to use |
| Outdoor sensors can be used either to | | | | depends on several factors: perceived threat |
| complement indoor security sensors or as | | | | and level of protection required; |
| primary security in situations where indoor | | | | effectiveness of the sensor against the |
| security is not feasible. Able to protect | | | | threat; site conditions and environment; |
| assets at both manned and unmanned sites, | | | | sensor cost-comparisons; and the life cycle |
| outdoor security sensors are a practical | | | | or cost of ownership of the sensor. Outdoor |
| solution for remote sites where guards are | | | | sensors can be classified into four groups: |
| not a viable alternative. | | | | volumetric sensors, fence-mounted sensors, |
| | | | video motion detection sensors and barrier |
| Outdoor sensors face challenges not found in | | | | sensors. |
| indoor security situations. Environmental | | | | |
| conditions, such as temperature extremes, | | | | Volumetric Sensors |
| rain, snow, animals, blowing debris, seismic | | | | |
| effects, terrain and traffic, must all be | | | | Volumetric sensors generate an invisible |
| taken into account. When functioning under | | | | detection field that locates intruders moving |
| these adverse conditions, the system must | | | | through that field. As the field of detection |
| continue to maintain a high probability of | | | | is invisible, these sensors are very |
| detection while minimising false alarms | | | | difficult to evade. Immune to most |
| (alarms with unknown causes) and nuisance | | | | environmental conditions, these sensors are |
| alarms (environment-related alarms), both of | | | | often used in sterile zones and may be |
| which can reduce confidence in the security | | | | totally covert. |
| system's performance. | | | | |
| | | | Fence-Mounted Sensors |
| The "vulnerability to defeat" characteristics | | | | |
| of different sensors is important to | | | | Fence and wall-associated sensors are above |
| consider. The hidden nature of totally covert | | | | ground detection sensors that are attached to |
| sensors makes them difficult to avoid and | | | | an existing fence or wall. They detect |
| less subject to vandalism. Intruders are not | | | | intrusion when an intruder disturbs the |
| even aware of their presence. On the other | | | | detection field or when vibration due to |
| hand, some sensors present an imposing | | | | cutting or climbing on a metal fabric fence |
| appearance that can provide a deterrent | | | | causes an alarm. |
| effect. Volumetric sensors create a large | | | | |
| invisible detection field that makes bridging | | | | Video Motion Detection Sensors |
| difficult. | | | | |
| | | | A Video motion detection system transforms |
| Closed circuit television (CCTV) cameras are | | | | the assessment-only ability of CCTV cameras |
| an important element in outdoor security. | | | | by analysing the video output signal to |
| CCTV assessment is used to verify whether or | | | | create the detection field. Video Motion |
| not alarms reported by intrusion detection | | | | Detection also provides additional |
| sensors are valid intrusions or false / | | | | information to help identify the source of an |
| nuisance alarms, ensuring that only valid | | | | alarm and whether or not it is valid. |
| alarms are responded to. Use of assessment is | | | | |
| especially important for remote sites where | | | | Barrier Sensors |
| response to nuisance alarms can be | | | | |
| particularly costly. | | | | Barrier sensors are a two-in-one security |
| | | | option. They provide both a barrier to |
| Security Management System | | | | intrusion and a sensor system for detection. |
| | | | Taut-wire sensors are an example of a barrier |
| Whether security requirements call for | | | | sensor that offers an almost zero False Alarm |
| sensors in stand-alone detection, or combined | | | | Rate and unsurpassed Probability of |
| with CCTV assessment in an integrated system, | | | | Detection. These sensors have virtually no |
| security management should be a | | | | environmental limitations and are able to |
| consideration. A security management system | | | | provide reliable service for many years. |