The Importance of Perimeter Monitoring
A perimeter monitoring system is a facility's first line of defense. By detecting intruders at the outermost boundaries of your facility, your security staff is better able to intervene in time to prevent serious loss.
Today, perimeter monitoring is especially important given the elevated threat levels we face in these uncertain times.
FIBER OPTIC FENCE [top of page]
Fiber optic fence systems, such as Fiber Fence, use light rather than electricity to detect intruders. During operation, light pulses are transmitted through fiber optic cable, which is typically installed on existing perimeter fencing. These light pulses are continually monitored for any change in light pattern or optical power, as may occur when the fiber is bent or broken during an intrusion attempt.
Fiber Optic Fence systems offer many advantages over other sensing technologies:
• Immunity to electromagnetic interference (EMI) - Compared to electronic, microwave, and electric field sensors, fiber optic sensors are not subject to interference from EMI.
• Safe for all environments - Fiber optic sensing cable does not carry or conduct electricity; it is safe for use around fuels, gases and combustible materials.
• Exceptional range - Fiber optic monitoring systems operate over far greater range than electronic sensing systems.
• Low incident of nuisance alarms - Fiber optic fence systems are not subject to interference due to small animals, adverse weather, changing light conditions, EMI, and so forth.
• Cost effective - Fiber optic sensing cable is easily incorporated into all types of existing fences and walls. The cable can also be mounted on posts as a stand alone system. Fiber optic sensors typically do not require electrical power in the field.
Unique Advantages of Patented Fiber Fence Technology
Some fiber optic fence systems are designed to detect breaks in the fiber optic cable. Other systems detect alterations in light patterns or optical power that result when bends occur in the fiber.
The patented Fiber Fence 3000 system is unique in that it detects both breaks and bends in fiber, and also reveals the exact location of an intrusion on a computer map. The system can also detect simultaneous multiple intrusions, as can occur in a coordinated assault.
MICROWAVE SENSORS [top of page]
Microwave sensors are used in both indoor and outdoor applications. Microwave systems work by covering an area with an electric field. Microwave sensors set off an alarm when movement in the zone disturbs the field.
Principal Drawback - Microwave sensors operate in the high frequency spectrum (X band). Proximity to other high frequency signals degrade the detection reliability of these sensors. Nuisance alarms may be caused by radio transmitters, electric motors, generators, and fluorescent bulbs.
Other Shortcomings:
• Component / installation costs
• Large metal objects such as dumpsters, electrical boxes, or trash cans can create "dead pockets" within the detection zone.
• Sensors require electricity
Fiber Fence Advantages over Microwave Sensors:
• Sensors do not require electricity
• Can be calibrated to eliminate nuisance alarms
• Immune to EMI - Not affected by radio transmitters, electric motors, fluorescent bulbs, etc.
• Economical to purchase
• Easy to install
Vibration sensors are transducers that detect low frequency energy, such as that generated by a physical intrusion attempt. The sensors are designed to detect mechanical vibration caused by such actions as sawing, drilling, chopping or ramming.
Principal Drawback - Walls or fencing to which the sensors are attached must have the proper composition and structural integrity to enable vibration to be transferred to the sensors. Certain types of wood, metal and masonry walls and fencing do not transmit vibration effectively enough for reliable intrusion detection.
Other Shortcomings:
• Nuisance alarms may result if sensors are exposed to vibrations caused by trains, planes, vehicular traffic or vibrating machinery.
• Sensors require electricity
Fiber Fence Advantages over Wall Vibration Sensors:
• Sensors do not require electricity
• Can be calibrated to eliminate nuisance alarms
• Can be mounted on virtually any type of fencing or wall
• Not affected by extraneous vibrations
• Economical to purchase
• Easy to install
AUDIO SENSORS [top of page]
Audio sensors detect noises generated by an intrusion attempt into a protected area. This type of sensor is typically used to monitor indoor facilities such as critical storage areas, entrance foyers, and so forth.
Principal Drawback - Audio sensors must be mounted in areas where the noise generated by an intrusion attempt is expected to exceed normal environmental noise. Since loud background noise is common in outdoor applications (e.g. passing vehicles, thunderstorms, aircraft over flights, etc.) audio sensors are typically not recommended for perimeter monitoring purposes.
Other Shortcomings:
* Intrusion attempts may not generate enough sound to trigger sensor
* Sensors require electricity
Fiber Fence Advantages over Audio Sensors:
• Not affected by environmental noise
• Sensors do not require electricity
• Can be calibrated to eliminate nuisance alarms
• Designed specifically for Perimeter Monitoring
• Economical to purchase
• Easy to install
ACTIVE ULTRASONIC [top of page]
This is a motion detection system that floods ultrasonic sound energy into a monitored area. An alarm is generated when a sensor detects a change in the reflected energy pattern.
Principle Drawback - An intruder moving slowly in the area of coverage may not be detected by the sensors.
Other Shortcomings:
• Extreme changes in temperature or humidity, common in outdoor environments, can degrade the sensors' ability to detect intrusions and/or result in nuisance alarms.
• Ultrasonic energy will not pass through certain objects, especially metal, which can create dead zones in the monitored area.
• Air movement and other stimuli can create noise near the ultrasonic range and trigger nuisance alarms.
* Animals and other moving objects can cause alarms.
* Sensors require electricity.
Fiber Fence Advantages over Ultrasonic Sensors:
* Sensors do not require electricity
* Can be calibrated to eliminate nuisance alarms
* Not affected by changes in temperature or humidity
* Extraneous sound in ultrasonic range will not trigger false alarms
* Economical to purchase
* Easy to install
PASSIVE INFRARED [top of page]
Passive infrared sensors work by detecting electromagnetic energy generated by sources, such as people, which produce thermal radiation different than that of visible light.
Principal Drawback - These sensors look for thermal radiation that is projected against a cooler background. Problems occur when the temperature of the environment approaches the same temperature as the intruder, who may not be detected under these circumstances. Since wide temperature changes occur frequently in outdoor environments, passive infrared sensors are not an ideal perimeter monitoring solution.
Other Shortcomings:
* Heat emitted by small animals can cause false alarms
* Vehicle headlights and other sources of focused light can trigger nuisance alarms
* Sensors require electricity
Fiber Fence Advantages over Passive Infrared Sensors:
* Sensors do not require electricity
* Can be calibrated to eliminate nuisance alarms
* Not affected by changes in temperature or humidity
* Extraneous light will not trigger false alarms
* Economical to purchase
* Easy to install
ELECTRIC FIELD [top of page]
Electric field sensors work by generating an electrostatic field between wire conductors and an electrical ground. Sensors are designed to detect distortions in the field, such as that cased by someone who approaches or touches the perimeter fence.
Principal Drawback - Adverse weather conditions, including rain, snow and lightning storms can degrade the reliability and performance of the system.
Other Shortcomings:
* High component / installation costs
* Animal movement and vegetation along the fence line can cause the
sensors to trigger.
* Sensors require electricity
Fiber Fence Advantages over Electric Field Sensors:
* Sensors do not require electricity
* Can be calibrated to eliminate nuisance alarms
* Not affected by electric field generated by lightning storms
* Not affected by rain and snow
* Economical to purchase
* Easy to install
PORTED COAX ("Leaky" Cable) [top of page]
This type of system uses a ported coax cable (typically buried) that has small holes in the outer shield of the cable. The purpose of these holes is to allow electromagnetic energy to radiate from the copper wire inside the cable, thereby creating an electric field in the vicinity of the cable. When an intruder or other object disturbs the field, a second parallel receiving cable senses the disturbance in the electric field and signals an alarm.
Principal Drawback - Subject to interference by sources of electromagnetic interference (EMI). Should not be used at electrical substations, around large electrical equipment, etc.
Other Shortcomings:
• Very high component / installation costs
• Nearby metallic objects, including metal fencing, can interfere with performance.
• Sites with heavy snowfall are prone to unreliable detection.
• Standing water over buried cables can generate nuisance alarms
Fiber Fence Advantages over Ported Coax Sensors:
• Sensors do not require electricity
• Not affected by electromagnetic interference (EMI)
• Can be calibrated to eliminate nuisance alarms
• Not affected by weather or standing water
• No trenching required
• Economical to purchase
• Easy to install
PHOTO ELECTRIC BEAM [top of page]
Photoelectric beam sensors are most often used for indoor applications, such as to protect doorways, windows and hallways.
Principal Drawback - These sensors are not well suited for outdoor applications such as perimeter monitoring. Fog, smoke, mist, and dust contain reflective particles that result in frequent nuisance alarms. Changing lighting conditions and blowing leaves can also trigger alarms.
Other Shortcomings:
* Sensors require electricity
Fiber Fence Advantages over Photo Electric Beam:
* Sensors do not require electricity
* Can be calibrated to eliminate nuisance alarms
* Not affected by fog, smoke, mist, etc.
* Operates under all lighting conditions
* Economical to purchase
* Easy to install
