Sanki Eng., Co., Ltd.

Hitachi Cable, Inc.

Shinya Ishi

Norihiko Shibata

Fumiaki Tsuchiya

Toshihiro Nozawa

Akinari Nakayama

Hideki Yagyu

Kiyoshi Watanabe

Shinji Hinoshita

Shigeru Iwata

Intrusion by climbing or jumping over a fence can be detected, and intrusion is detected in a wide area without large-scale equipment. FBGs (grating sections) of different types having different refractive indexes of fiber glass are arranged at predetermined intervals in a longitudinal direction of optical fibersA, andB, the optical fibers are laid down between poles on the top of a fence or a side thereof, reflected waves from the FBGs are issued by photodetection devicesA, andB in response to an optical input to the optical fibers, and a wavelength shift detection devicedetects a position of an FBG which exhibits a wavelength shift by swinging of the optical fibers by a stress acting on the fence. A pattern recognition devicefetches positions of the wavelength-shifted FBGs as differences between timings of the pulse signals and discriminates swinging of the fence caused by intrusion from swinging of the fence caused by other factors on the basis of output patterns of the pulse signals.

Break-in detection sensor

A break-in detection system includes a detection sensor of an FBG type for detecting an intruder trying to climb over a fence around a premises, and a detection sensor of an OTDR type for detecting an intruder trying to demolish the fence. A fiber optic cable used as a detection sensor has a sensor core wire and a LAN transmission core wire arranged in parallel to form a LAN transmission channel. The LAN transmission core wire transmits videotaped image signals from ITV cameras and image control signals two ways between a monitoring room and an ITV control device. The LAN transmission channel is available for connection by IP telephone sets, a LAN terminal, a wireless LAN terminal, and an IP-BOX for internet communication. The system has excellent reliability and maintenance-free characteristics.

Break-in detection system

In an unshielded twisted pair cable, a predetermined number of pairs which are twisted by a predetermined lay-length are covered by a protective sheath. Insulations for insulating conductors for the pairs and the protective sheath are wholly or partially of halogen free polymer having a low dielectric loss tangent and flame-retarding properties. The insulations have a dielectric loss tangent of less than 1.times.10.sup.-2 at 150 MHz and a 2% modulus of at least 0.3 kgf/mm.sup.2.

Unshielded twisted pair cable

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Hitachi, Japan

Shinya Ishi