British Telecommunications Public Limited Company

British Telecommunications Corporation

The Post Office

Michael H Reeve

Stephen A Cassidy

Stephen Hornung

Raman Kashyap

David B Payne

Simon M James

Lawrence Bickers

Paul Adrian Rosher

Anthony James Cooper

Simon Charles Fenning

Colin A Millar

Mark Davison

A transmission line, such as an optical fiber (or wire) transmission line, is installed by first installing a conduit having one or more bores and subsequently inserting flexible, lightweight optical fiber members containing the optical fibers into the bores. The optical fiber members are propelled by employing the fluid drag of air, or another suitable gas, passed at high velocity through the bores.

Method and apparatus for installing transmission lines

Method and apparatus for installing transmissions

An optical fibre communications system includes an exchange (E) and a plurality of subscriber lines (1). The exchange (E) provides a plurality of services in different subcarrier frequencies (6,8,9,10). Each subscriber line (1) is provided with terminal apparatus (5) operable at different subscriber frequencies, and a control (11) at the exchange (E) tunes the terminal apparatus to transmit and/or receive on a particular frequency in response to a request. The request may be a signal from the terminal apparatus (5), or an incoming service request addressed to the particular terminal apparatus.

Optical fibre communication system

A transmission line, such as an optical fibre (or wire) transmission line, is installed by first installing a conduit having one or more bores and subsequently inserting flexible, lightweight optical fibre members containing the optical fibres into the bores. The optical fibre members are propelled by employing the fluid drag of air, or another suitable gas, passed at high velocity through the bores.

A sheath for optical fibres comprises a compound sheath having an inner sheath of high modulus and density, and an outer sheath layer of low density material. The outer sheath layer may be of foamed polyethylene and the inner sheath of polypropylene, both conveniently formed by extrusion. Such fibre members are installed by first installing a conduit having one or more bores and subsequently inserting the flexible, lightweight optical fibre members containing the optical fibres into the bores. The optical fibre members are propelled by employing the fluid drag of air, or another suitable gas, passed at high velocity through the bores.

Sheathed optical fibres and method of installing such fibres

Optical coupling device

An optical fibre has a coating of, for example, liquid crystal polymer which causes temperature-dependent stress-induced changes in the optical fibre such as to counteract temperature-induced changes in the transmission delay of the fibre.

Temperature desensitization of delay in optical fibres

An optical fibre transmission line is installed by first installing a conduit having one or more bores and subsequently inserting flexible, lightweight optical fibre members containing the optical fibres into the bores. The optical fibre members are propelled by employing the fluid drag of air, or another suitable gas, passed at high velocity through the bores.

Optical fibre transmission lines

Optical fibre transmission line

A pair of optical fibres which are to be joined are located with their end portions in coupling elements one of which is transparent to light. The coupling elements are located such that the ends of the fibres are in approximate alignment. Light is transmitted along one fibre so that it is received by the fibre in the transparent coupling element. Light which is not coupled into the core of the fibre is sensed by a sensor and the relative position of the fibres is adjusted until the level of sensed light is a minimum. The sensing of the light is carried out at positions spaced angularly about the waveguide so that an indication of the direction of any misalignment is obtained. The coupling elements are then secured in this position. The adjustment of the fibres can be carried out using a linear translation stage and a microprocessor which controls the stage in accordance with signals from the sensor.

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Ipswich, United Kingdom

Michael H Reeve