Switched changeover between optical data transmission lines

摘要

An optical fibre data transmission system has a bidirectional facility in which a number of lines (9,10,11 and 12,13,14) can be selectively connected between transmitters (5,7) and receivers (6,8). The transmitters and receivers selectively access the lines with the aid of optical switches (1-4) operated by control units (17,18). The latter detect any faults, e.g. line faults, and an alarm is signalled. Simultaneously, change-over between lines used for transmitting data is initiated.