| 摘要 |
A fault signalling system for an optical fibre-based communications link having erbium doped fibre amplifier repeaters (20) comprises a broadband optical source (34) for generating a fault signal in the event of a fault occurring. Each repeater includes such a broadband source, which will output a characteristic fault signal onto the link for transmission to a receiving station, in the event of a fault being detected at that repeater. Advantageously, a control circuit which enables the source (34) to emit its fault signal when appropriate is also used as part of an automatic gain control for the output of the amplifier repeater in normal operation. |
