Monday, May 14, 2007

The Transition of the Low Tech Fence
Robert Gruber, PSP
Master Halco Security Solutions Group

Yesterday I saw a cartoon picturing the US / Mexican border in the background, with new 20' fencing being installed. In the foreground was a ladder shop with a gentleman up on a ladder changing his signage to read, "New - 21' Ladders on Sale." Obviously, the illustrator hasn't kept up with the state of the art in perimeter security. Even low tech basic fences have reached geek level.

In the past, that 21' ladder may have been a solution for climbing over a fence, but today it will take more than one ladder to get through a perimeter barrier. Just a few years ago, the fence itself was the perimeter security. Now, the fence is the basic building block of the perimeter security solution--the foundation for adding intrusion detection measures.

First, the physical structure of the fence itself is more diverse. The fence can be chain link, welded wire (welded on just one side or both sides), or it can be razor mesh to make handholds an impossible option for intruders or unauthorized personnel. It can be designed as a stun fence or perhaps even lethal to the touch. You can install a see-through fence or choose privacy to inhibit who or what can be seen on the other side.

Next, intrusion detection systems are now designed to attach to the fence or near it. This can include potential underground wire / electromagnetic sensors or fiber optic sensors. The electromagnetic sensor puts a "balloon" of energy up over the ground near the fence, and when a metallic substance passes through, an alarm can be activated. Most humans carry metallic substances. The fiber optic type of sensor is one which will compress when there is a weight pressed over it - the nature of the light traveling through the optic will change with the compression. Other "near the fence" methods include infrared, microwave, radar, or LIDAR methodologies (LIght Detection And Ranging, a new type of "light" radar).

Intrusion detection options located on the fence range from the basic--a simple taut wire system-to more complex technology. The principle of taut wire is simple: if the fence is tensed, such as when someone climbs it, the wire becomes more taut, and the sensor activates. Mechanical or electromechanical sensors such as shaker systems can also be installed. These are simple in technology, and are based on the movement of a loose part, such as a ball bearing, inside a container. The overall system has a certain resistance characteristic, and when the movement takes place, the resistance changes. With a change in resistance, messages can be sent to a control point to activate a prepared response.

Much more sophisticated sensors can be added to the fence as well. Some fence wire is hollow and sensor material can be built into the wire itself. Parts of the fence can be made to be positive and negative plates of a capacitor - when something interferes with the distance between these "plates," capacitance changes. The change in capacitance creates an electronic message for sounding an alarm. You can also incorporate fiber optic or copper wire into the fence--different principles of operation, but all are effective. Deciding which to use depends upon your security needs, geographical location, and weather patterns.

These smart fences can attach to a wide area communications network to send an automatic message if any type of problem takes place at the perimeter. This "message" can even be sent through the Internet to a person's handheld operator. For the corporate environment, the perimeter security solution can be incorporated onto the company's Local Area Network (LAN) just as building security has been incorporated into the IT realm.

Additionally, smart fences can be used to support other structures such as a lighting system--lighting that is activated by movement taking place at the fence. For those very remote areas, the lighting can be powered by solar panels. These panels now have the ability to store about 5 days of power within the lamps--much more than is typically required for security applications. Likewise, video can start recording by activity at the perimeter--not just any video, but the new analytic technology which can track movement via intelligent pan, tilt, and zoom. These cameras can even hand off activity from one camera to another just as a cell phone hands off a conversation from one cell phone tower to another.

The old style perimeter barrier using only a fence involved constant human patrols just to see who may be trying to climb over the barrier and to monitor areas of damage (either as a result of human interference or through general wear and tear) for maintenance. The new "smart" fence doesn't require human involvement at the perimeter, necessarily, depending upon the overall objectives in a company's security plan. So, I'm sorry Mr. Salesman, you've got to do better than building a taller ladder. The low tech fence, while still a viable barrier option for commercial and industrial applications, is giving way to the smart fence of the 21st century.