British Telecommunications Public Limited Company

British Telecommunications Corporation

Lutz C Blank

David M Spirit

Andrew Lord

Apparatus and a method for increasing the optical measurement range in optical time domain reflectometers in which a fibre laser amplifier is used to amplify the optical time domain reflectometer pulses launched into a waveguide. This apparatus and method have particular usefulness for branched local networks. The signal returning to the optical time domain reflectometer is amplified as well as the outbound signal.

Optical time domain relectometry with optical amplifier for extended

OTDR using distributed optical amplification in optical waveguide under

A submarine optical telecommunications system has two shore based transmitting stations whose signals are combined at a passive, submerged junction. Phase errors are caused by variations in transmission times to the junction. An error signal is generated at the first repeater after the junction. The error signal, which represents the phase errors, is transmitted to a shore station where it is used to adjust the sending phase. A surface acoustic wave filter tuned to half the frequency of the combined signal is the preferred way to generate the error signal.

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Colchester, United Kingdom

Lutz C Blank