Frequently Asked Questions

General Information

Q: Who uses these systems?
Fiber SenSys systems have been installed at hundreds of sites around the world. Users range from the Department of Defense, the State Department and Department of Corrections, to commercial and high-end residential property owners. Applications include fences, buried zones, walls, rooftops, ductwork, ceilings and many others.

Q: How do these systems work?
Using special optics, an optical fiber can be made very sensitive to motion, vibration or changes in pressure. When the fiber is attached to a structure, such as a fence, it will be able to detect disturbances caused by someone attempting to cut or climb the fence. When the fiber is buried under gravel or sod, it will detect pressure changes when someone walks or crawls over it.

Q: Must the fiber cable start and end at the same point?
Yes and no. For a single zone system the answer is yes since both the laser light source and the optical detector are included in the Alarm Processing Unit (APU). The cable is laid out so that it starts at the laser, runs through the detection area and then returns to the detector. We call this a "loop-back" installation. For multi-zone systems, the answer is no. Fiber cable can run from the laser light source of one APU to the optical detector of the next APU and continue in this fashion down the line. We call this a "daisy chain" installation.

Q: Can I install the fiber so that part of a zone is buried and part is on a fence?
No. Each zone is adjusted based on the conditions and background noise that it experiences. Buried and fence applications require very different settings on the Alarm Processor. The FD-332 and FD-342 are dual-zone processors, which means, they provide two independently programmable zones. One of which can be buried, while the other is attached to the fence.

Q: You claim that Fiber SenSys intrusion sensors are highly resistant to nuisance alarms. Why is this true?
There are a number of factors that contribute to the rejection of nuisance alarms in our systems. First is the fiber cable itself. Optical fiber is not affected by EMI, RFI or lightning that can cause disturbances in electrical or radio frequency sensing systems. The cable contains no metal and will not conduct electricity. The second reason is the sophisticated, microprocessor-based Alarm Processing Unit (APU). The APU converts the optical signal from the sensor to an electronic signal and looks at the intensity, duration and frequency, along with several other factors, to determine if a signal is the result of an actual intrusion or is from a nuisance source such as traffic, wind or small animals. Since every installation is unique, the APU has over 30 adjustable parameters to give optimal performance in any situation. Finally, for structures located in very windy areas, Fiber SenSys offers an optional anemometer that feeds wind speed data into the APU so that adjustments for wind noise can be made automatically.

Q: How many zones does each Alarm Processor support?
Each APU supports a single zone. The FD-332 and FD-342 are dual-zone processors.

Q: Will the system tell me where in a zone an intrusion is occurring?
No. It will only tell you that an intrusion is taking place somewhere in the zone.

Q: How large are typical zones?
It varies based on the needs of the user. For high security systems where immediate response is required, typical zones are not much more than 300 feet. This allows a single camera or guard to respond immediately when an intruder is detected in a zone. For commercial systems, zones may be much larger, up to our system’s maximum range of 16,400 feet. This is much more economical than shorter zones and is often just as effective when camera coverage is limited or when police or security guards are expected to take several minutes to respond to an alarm.

Q: What is the difference between an FD-331 and an FD-341 Alarm Processing Unit?
The FD-331 supports only sensing cable. The FD-341 allows for remote mounting of the APU with insensitive fiber-optic cables running out to the sensing zone.

Q: How far away can the FD-208 or FD-340 be located from the sensing zone?
The insensitive fiber can run as much as 12.4 miles from the APU to the sensing zone.

Q: Can Fiber SenSys Alarm Processors be mounted outdoors?
Yes. Specify part numbers ending in E, i.e.: FD-332E or FD-342E, to have the Alarm Processor mounted in a NEMA class 4X weatherproof enclosure with a tamper switch.

Q: Can the FD-208 use an anemometer?
No. Due to the remote capabilities of the FD-208 and the FD-340 series, the anemometer would not be affective. However, all Fiber SenSys APU’s employ sophisticated on-board wind processing software.

Q: How do I program the Alarm Processing Unit?
Fiber SenSys offers several methods for programming our Alarm Processing Units. First, is our SpectraView software which provides tools for monitoring, calibrating, and recording perimeter activity. Fiber SenSys now offers Hyperion! A compact version of our popular SpectraView software housed in a ruggedized pocket PC. An MC-200 rugged terminal is also available for manual programming.

Q: Do I need any special tools to install Fiber SenSys systems?
Yes, there are a few special tools required. To attach the conduit to a chain-link fence, you need our wire twist tool, part# EZ-370. To install cable into our split conduit, use the insertion tool, part #EZ-350. To install fiber-optic connectors, you need to use installation tools from the connector manufacturer. (Fiber SenSys sells connectors made by AMP and also offers an AMP installation tool kit.) Finally, to program the processor, you will need either our hand-held calibrator or a lap-top computer.

Q: What are the power requirements for a Fiber SenSys system?
Alarm Processors require 12 or 24 VDC power. Each APU draws less than 250 mA at 12 VDC during continuous operation but can spike as high as 2 A at 12 VDC for a very brief time during start-up. The FD-208R, Rack-mounted APU uses 120-240 VAC at 1A, 50-60Hz.

Q: How do I tie the alarm signal from a Fiber SenSys unit into my security system?
The Alarm Processor provides normally open and normally closed dry contacts for alarm or tamper signals. These can feed into a larger system using copper wiring or a radio link. Optionally, you can use the Fiber-optic Security Network, (FSN) from Fiber SenSys to bring alarm information from many zones back to a central point using optical fiber. The FSN will provide relay contacts corresponding to each zone for alarm panels or an RS-232 output for computerized head-end systems. The FD-300 series also offer a TCP/IP option, which can report alarms and status through a TCP/IP network using the Extensible Markup Language (XML) protocol.

Fiber & Connectors

Q: Is special fiber-optic cable required?
Yes. For applications which use conduit, 3 mm sensing cable is required (part# SC-3). For applications which require direct burial of the sensor cable, 4 mm sensing cable is required (part# SC-4). The outer jacket provides stability and increases the lifespan of the fiber in all weather conditions.

Q: Are special fiber-optic connectors required?
No. Standard ST bayonet connectors are all that is required. These connectors are commonly used for telephone and CCTV systems. We do suggest that you use connectors with ceramic ferrules in order to assure consistent performance over temperature. Fiber SenSys does NOT recommend the use of non-polish connectors such as Unicam. These connectors are not rated for outdoor applications.

Fence Installations

Q: How do I install the system on a fence?
Slide the fiber cable into our flexible split conduit and attach to the fence fabric with cable ties. For non-split conduit, a pull cord is provided to pull the fiber into the conduit.

Q: What about gates?
For swinging gates, the flexible conduit can run out on the gate and then loop back to the hinge area so that it will swing with the gate. You can continue the run without a break by burying the cable in rigid conduit about 18 inches below the gate and coming up on the other side. (The installation manual gives more details and illustrations.) Sliding gates are more difficult. They can be covered with our system if cable is attached to the slide or support rail that the gate rests on. Movement of the gate will be transmitted to the rail and therefore can be sensed. Some trial and error is required to determine the right amount of fiber to make the gate sensitivity similar to the rest of the fence. For complicated or difficult gates, we recommend that you bypass them and use a small beam or other device to protect them.

Buried Installations

Q: How do I install a buried zone?
Determine the area to be protected and bury the cable, part # SC-4, about three inches below the surface in a back and forth, or serpentine pattern.

Q: Can I install a buried sensing cable under asphalt or concrete?
No. There will not be enough energy transferred to the cable. The buried zones are limited to gravel or soil that will transmit energy to the sensing cable.

Q: How large should a buried zone be?
Buried zones typically range from three to ten feet wide. If you know where an intruder is likely to step, i.e.: next to a fence or wall prior to climbing, then the zone can be narrow. In an open field, zones are typically wider.

Q: How closely should buried cable runs be spaced?
This depends on the type of soil. In gravel, typical spacing is around 18 inches. Under sod, spacing is usually around 12 inches.