| 摘要 |
In an intrusion detection system, at least one optical cable is provided, through which light enters at one of its ends and exits at the other end, at which other end a device for detecting changes in the light intensity passing through the cable is also provided. The system is usually part of a fence, but it can be used in structures such as roofs, windows, etc. When an intruder exerts force on the optical cable, its movement actuates a mechanical device so that a member thereof exerts pressure at a certain place on the cable, deforming the optical cable and causing light attenuation which is detected and actuates an alarm. When used as part of a fence, such mechanical sensing devices are provided at certain intervals from each other. Optical cables can be provided at different heights of such a fence, with light intensity attenuation means as described above.
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