Supervisory signalling for optical communications equipment

摘要

A method and apparatus for supervisory signalling relating to submarine optical communications equipment on a submarine optical communications system. Status information on an optical transmission line used to transmit a data signal is transmitted by applying a control signal to an optical attenuator through which the data signal passes. The attenuator modulates the data signal by a signal corresponding to the status information. The status information could be, for example, information regarding a branching unit coupled to the optical transmission line or regarding an optical equaliser coupled to the optical transmission line.