Editing Security alarm (section)

===Fiber optic cable===
A fiber-optic cable can be used to detect intruders by measuring the difference in the amount of light sent through the fiber core. A variety of fiber optic sensing technologies may be used, including [[Rayleigh scattering]] or [[interferometry]]. If the cable is disturbed, the light will change and the intrusion is detected. The cable can be attached directly to a chain-wire fence or bonded into a barbed steel tape that is used to protect the tops of walls and fences. This type of barbed tape provides a good physical deterrent as well as giving an immediate alarm if the tape is cut or severely distorted.

Being cable-based, fiber optic cables are very similar to the microphonic system and easy to install and can cover large perimeters. However, despite performing in a similar manner to microphonic-based systems, fiber optic cables have higher cost and is more complex due to the use of fiber-optic technology.