The Fiber DefenderTM Model FD322 is a value-priced, easy-to-use, high-performance fiber-optic intrusion sensor designed to detect intruders that are cutting through, climbing over, or crawling under a perimeter fence.

Each alarm processing unit (APU, see figure right) supports two zones, and each zone can support up to 500 meters of sensing cable. An optional tamper-proof enclosure is available for easy mounting at the perimeter.

The sensor element is a rugged multimode optical fiber integrated into a specialized cable and installed inside conduit that is attached to the fence using stainless steel wire. This configuration results in an extremely robust fence-mounted sensor that is unaffected by rain, hail, salt spray, or humidity. The fiber optic sensor, cable, and conduit are dielectric and 100% passive so they can be used in areas with high electromagnetic interference and/or areas with flammable/explosive materials.

The fiber-optic sensor is especially applicable to areas frequented by severe thunderstorms and lightning because the optical fiber cable/conduit will not conduct electrical discharge back to the APU, and because the sensing fiber is unaffected by EMI resulting from lightning strikes.