Data communication between stations over unidirectional loop - uses optical fibre links between adjacent stations connected together by ring main

摘要

A number of stations (1, 2, 3) communicate with each other over optical fibre links. The links are connected together to form a complete loop and information passes round it in one direction only. At each station, the incoming fibre is terminated by an optoelectronic transducer and amplifier and the outgoing fibre (5) is driven by another. The two transducers are normally connected together by a switching circuit. Each station monitors all the communications passing round the loop and intercepts those addressed to it. When a station wishes to send messages, it operates its switching circuit to break the loop and connect the outgoing fibre to its own transmitter. The transducers are amplifiers all receive their power supplies from a ring main (4) running in the same conduit as the optical fibre and fed at one of the stations.