Perimeter Protection: One Size Does Not Fit All

Today’s security professional can choose from a wide range of perimeter detection sensor technologies to address a wide range of threat scenarios.

“One product does not fit all and in correctional facilities, you will see a combination of taut wire barriers, fence detection technology and covert systems to provide an overall solution,” says Martha Lee, president of Magal-Senstar Inc., an outdoor perimeter security company. “Environmental conditions, site constraints, nuisance alarm considerations and regulations are the factors that facility management need to address and assess when choosing a system.”

There are five basic elements to be considered when choosing an outdoor perimeter security system:

Deter. A perimeter should be designed so that it clearly creates boundaries in the protected area, while discouraging access to that area. In the case of correctional facilities, boundaries are created with 12-foot fences with concertina wire, which will deter most inmates from escape attempts.

Perimeter sensor products that deter people from intruding or escaping include freestanding, fence-mounted or buried systems. Most correctional facilities use a combination of the three — walls, fence sensors and a covert system, such as buried cable.

Detect. When access to the protected area or boundary occurs, an outdoor perimeter sensor system provides an early warning that unauthorized entry has taken place. A covert buried cable system can identify individuals by mass and volume and alert security personnel of an escape attempt.

Overt systems are also available with copper-based or fiber-based sensor technologies that are applied to existing fences or barricades. They can detect intruders climbing on, cutting through or lifting the fence fabric.

Delay. It is necessary to have an adequate delay capability to allow proper assessment of the intruder or escapee, as well as to delay him or her from reaching critical assets or escaping. A perimeter security system at a correctional facility should be placed in areas that allow personnel the time they need to reach the point of contact once they have been detected. The typical delay mechanism is a physical barrier that is extremely difficult to defeat or penetrate.

Assess. All alarms triggered by a security system need to be assessed to confirm validity. Many assessment methods are susceptible to environmental conditions. Sensor technologies can be designed and calibrated to rule out false alarms such as interferences caused by blowing snow, wind, rain, etc., and confirm real alarms posing a threat. This provides for greater accuracy in assessment of a threat. In extreme environmental conditions or areas where small animals cause nuisance alarms, technologies can be adjusted.

Respond. Appropriate action must be taken based on the assessment of the situation. The alarm sent to a control-and-display system at the correctional facility should give security personnel the exact location an inmate escape path so even in poor weather conditions, officers could get to where they need to be.

Selecting Perimeter Security Products

There are five sensor technology factors to consider when evaluating a perimeter security application against a threat:

Configuration. Sensors can be free-standing, fence-mounted or buried.

Overt/Covert. Visible sensors will act as a deterrent and are typically easier to install and maintain, but may be more susceptible to vandalism. Covert sensors are more difficult to detect and defeat. In the case of a correctional facility, a combination of the two is a good approach.

Sensing mode. A sensor is either line or volumetric. The line-detection zone is confined to a well-defined line or plane and is visible and easy to locate (such as a wall or fence with sensor technology). Volumetric zone sensors detect intruders in a volume of space that can be either above or below the ground. Typically, the detection volume is not visible and more difficult for the intruder to locate in a terrain-following system.

Line-of-site/Terrain-following. Line-of-sight sensors (i.e. microwaves) require terrain that is clear and flat. A terrain-following sensor works well with uneven terrain and even terrain.

Active/Passive. Sensors operate in either an active or passive mode. Active sensors transmit energy and detect a change in received energy entering a field or perimeter space. Passive sensors detect energy caused by an intruder through vibration, heat, pressure or other physical movements.

Challenges

One of the core challenges that perimeter-sensing technology faces is environmental conditions and the ability to withstand local extreme weather conditions that can cause alarms. The other challenge can be nuisance alarms affiliated with motion around perimeter protection that is not a threat.

One size does not fit all for perimeter security systems. There is no single product solution, but rather a combination of technologies and choices to meet individual facility needs.

Cathy McHugh is the director of Marketing for Senstar-Stellar and MSi. She can be reached at cmchugh@senstarstellar.com . For more information, visit www.magalsenstarinc.com.