Technological advancements are happening everyday. They have changed the way we get our information, communicate with each other, and how we keep ourselves and property secure. In the next few pages the focus will be some of the technological advancements in outdoor and perimeter security. How have photoelectric beams changed? What's new with fiber optics? What are some the trends on the horizon? Also, what is important to the end-user in an outdoor security system?

Needs and Wants

"If it is a residence, people are worried about burglars, trespassing, etc. If it is, say, a maintenance yard the owner is worried about people climbing over fences and cutting the fences to steal," says Philip Fischer, vice president of sales and marketing, Fiber SenSys Inc., Beaverton, Ore.

People want to feel safe and secure in their homes. They want their property protected from intruders. They also want their needs met with a system that is easy to use, can do the job well, and isn't an annoyance.

"No matter what the market is (for example, airports, residences, commercial sites) people want outdoor perimeter security for the same reason: to provide advanced warning that they are about to come under attack from criminals [or] that their property is being trespassed on. It is all about being notified that an event is underway as soon as possible, so that there is time to react appropriately to stop the threat and have a better chance at catching or scaring off the intruder," says Michael Rack, vice president of marketing and business development, Senstar-Stellar Corp., a Magal Group Co., Fremont, Calif.

Customers don't want a system that is obtrusive and detracts from the look of their property or draws attention to the security system. Nor do they want a system that alarms with the slightest variation in weather conditions, when Rover is roaming around in the yard, or when customers are moving equipment around at their business.

"People want a security system that provides the best combination of the following: the highest probability of detection, the lowest false and nuisance alarm rate and the lowest vulnerability to defeat. In some cases they want sensors that not only detect intruders, but impose a barrier to intimidate intruders. In other cases, they want a sensor that is completely invisible for security or aesthetic reasons," Rack says.

Courtney Harris, marketing manager at Optex in Torrance, Calif., adds: "People want a system that is reliable, immune to environmental distractions and successful at making the home/building a more risky target for a successful break-in. By an outdoor sensor's use as a pre-warning device, this can be made possible. People also want to rest assured that an outdoor system can co-exist with one they already have. With the ability to perform several functions, such as activating a surveillance camera, turning on lights at the immediate detection of an intruder, or sending a signal to a remote central station for monitoring, an outdoor security system can add value to a pre-existing one."

There are a lot of products on the market for outdoor and perimeter security. Many of these devices got their start in the military and special government applications, which have made them able to withstand harsh weather conditions. Manufacturers have taken the government's electronic devices and improved upon them for civilian applications.

Some of the broad categories of outdoor security systems include: gates and fences, passive infrared detectors, dual technology sensors, photoelectric beams, CCTV, infrared illuminators, fiber optics, video motion detection and tracking, buried cable detection sensors, and security lighting. This article covers some of these categories and their developments.

Photoelectric Beams

Photoelectric beams transmit a beam of infrared light to a remote receiver. This creates an invisible "electronic fence." These sensors are often used in openings such as doorways or hallways. Once the beam is broken an alarm signal is generated. They have two components: a transmitter and a receiver. The transmitter uses an LED as a light source and transmits a constant infrared beam of light to the receiver. The receiver consists of a photoelectric cell that detects when the beam is present. An alarm will sound if the receiver doesn't receive at least 90 percent of the transmitted signal for at least 75 msec.

There are a bunch of manufacturers that make photoelectric beams and products. Some of these manufacturers include Ademco (Syosset, N.Y.), Detection Systems (Fairport, N.Y.), Pulnix, (Sunnyvale, Calif.) New Line Technologies (Bloomfield, Conn.) and Optex.

Optex, for example, manufactures a new short-range photoelectric detector, the AX-100/200 series, which has an alarm indication LED in the viewfinder. The LED comes on when the beam energy from the transmitter is not reaching the receiver, and turns off when the energy is reaching the receiver. It also has fine angle adjustment for alignment. The rotating dial allows the installer to finely adjust the beam horizontally or vertically with or without the use of a screwdriver. It has rain, dust, insect, frost and dew protection. The high grade aspherical lens creates a sharply defined and precise infrared beam. It also has an adjustable beam-interruption period. The amount of time a beam must be broken for an alarm to occur can be adjusted.

Fiber Optic Networks

Fiber optic networks detect low vibrations caused by a physical attempt to enter the structure on which the fiber is mounted. A fiber optic cable acts as a line sensor and it contains an electro-optics unit. The electro-optics unit transmits light using a light emitting diode (LED) as the light source. The light travels throughout the fiber optic network and is picked up by a detector, which is sensitive to slight alterations in the transmission. When an alteration in the light pattern takes place, the signal processor then generates an alarm.

Fiber SenSys' Fiber Defender 208 is new on the market. The FD-208 combines the ability to remotely locate all control electronics up to 10km for the protected zone with the digital signal processing algorithm. "Dual processors check all sensor signals in real time against 18 different user-adjustable evaluation criteria before triggering an alarm," says Duane Thompson, product manager, Fiber SenSys. The fiber optic sensor cable used with the FD-208 is immune to electrical interference, which is particularly important for installations near high-voltage electrical equipment. This product can be used where flammable gases and similar hazardous materials may be ignited, because it doesn't need any electricity at the perimeter zone.

Another new fiber optic product on the market is the DVM-2500 bi-directional video, audio, and data fiber optic multiplexer from Multidyne, Locust Valley, N.Y. The system supports one video, six audio and four data channels bi-directionally over one fiber. The video signal to noise ratio is greater than 75dB and a signal to quantizing noise ratio greater than 71dB. The video bandwidth is 8 MHz. The optical budget exceeds 30 dBm. It supports 24 Bit stereo audio flat from 20 to 20 KHz. Applications for this product include surveillance, common carrier transport, distance learning, and more.

PC Control of Security

"The biggest trends in security relate to integration or multiple sensors and other devices into a complete solution. Major advances in perimeter security technology over the last few years have meant smarter tech tools for security professionals to secure and monitor the boundaries of their facilities with new devices with inherent communications abilities seamlessly with bi-directional communication between the perimeter and the central control station," Rack says.

MicroPoint Cable by Southwest Microwave, Tempe, Ariz., detects any fence disturbance and locates it to within 10 ft. It also transmits alarm signals and operating power to all modules and auxiliary sensors along the perimeter. The software interfaces directly with a PC, so the PC becomes the installation test, graphic map and alarm monitoring display.

The Piramid XL by Protection Technologies, Inc., Reno, Nev., uses a microprocessor to insure consistency from sensor to sensor. The motion sensor has full digital signal processing and digital range adjustment. A popular configuration is to use the sensor with video surveillance and video verification systems, the sensor is used to activate recording equipment. In verification systems, Piramid XL is used to trigger cameras that initiate transmission of pictures of the protected area over phone lines to a central station.

The Rayonet 2000 by Smarter Security Systems Inc., Atlanta, is now supported by PC software. The 2-meter-high infrared "fence" (six closely spaced invisible beams) operates via

the Busmaster multiplexer and an RS485

data bus, which connects serial ports of

up to 16 zones via a shielded twisted pair.

The software adds several functional capabilities to the control and servicing of an outdoor perimeter security system. The system observes all beams simultaneously and allows the

control center operator to profile each zone according to specific needs. Settings can be simply uploaded to the tower using the

data bus.

There are a lot more cutting-edge and

highly effective outdoor and perimeter security products on the market. Integration and high-tech tools seem to be key to the future of outdoor and perimeter security.

SIDEBAR: Buried Cable Intrusion Detection Sensor

One of the most innovative, secure and widely installed perimeter intrusion detection technologies is the buried "leaky coax" intrusion detection sensor. Michael Rack goes on to discuss how the technology works. The system uses ported ("leaky") coaxial sensor cables to create an invisible electromagnetic detection field. A gap in the transmit cable outer conductor allows electromagnetic energy to escape and be detected by a corresponding parallel receive cable. The cables can be buried in any medium such as soil, sand, clay, concrete or asphalt to form a uniform, covert, volumetric detection field that is terrain-following.

The resulting detection field is typically one meter high and up to three meters wide. When an intruder disturbs the field, an alarm is declared. If networked, the alarm is instantly communicated over the sensor cables to a PC-based central control system.

The system uses a large volumetric field to detect moving targets based on their electrical conductivity, size and movement. Unless a target possesses the minimum alarm characteristics, it will not be detected. Thus, a person or vehicle crossing through the field is detected while small animals and birds are ignored. Adaptive algorithms filter out common environmental false alarm sources such as foliage, rain, snow or blowing sand and dust.

Such intelligent signal processing provides one of the highest probability of detection rates of any sensor type. Combined with the fact that it is not affected by vegetation, rain, snow, hail, sandstorms, wind, fog, temperature changes, RFI, EMI, seismic vibration, acoustic or magnetic effects, this type of sensor has an extremely low false and nuisance alarm rate.

After the cables are installed and the site is returned to its original condition, the volumetric detection field is completely invisible and extends both above and below ground. Since the detection field is invisible, intruders are unaware that the sensor is there. They cannot locate, avoid or tamper with it. These inherent features, in combination with the sensor's advanced technical capabilities, result in a low vulnerability of defeat.