Test equipment for testing an optical fibre transmission system

摘要

A test equipment for testing an optical fibre transmission system in which at the transmitting location a laser transmitter 1 is caused to transmit a synchronizing signal by operation of a key switch 2 but only when no data is being transmitted. At the remote location of the transmission line the synchronizing signal is detected and as a result a logic signal is outputted which may be displayed by light emitting diode. The logic signal can be transmitted by means of a stand-by circuit on a further wavelength in a reserve channel of a multi-channel signal to the location at which the test has been initiated.