Monitoring and/or controlling device and process

A method of controlling and/or monitoring an optical transmission of message signals over an optical line, said optical line comprising at least one optical repeater station (40, 50) connected between optical wave guides (10), said method comprising the steps of:

• a) transmitting the message signals and optical secondary signals acting as monitoring and/or control signals over said optical line;
• b) providing said at least one optical repeater station (40, 50) with a device (45) for generating further optical secondary signals to be transmitted from said at least one repeater station from said optical secondary signals received in said at least one optical repeater station, said device (45) comprising a hybrid circuit (451) for splitting the received optical secondary signals, an optical monitoring and/or control receiver (454) for providing control and/or monitoring signals (456) and an optical modulating device (458) controllable by the control and/or monitoring signals;
• c) splitting the optical secondary signals received in the at least one repeater station (40,50) by means of the hybrid circuit (451) to form a first branched optical signal portion and a second branched optical signal portion;
• d) providing the control and/or monitoring signals (456) by the optical monitoring and/or control receiver (454) receiving the first branched optical signal portion;
• and
• e) producing the further optical secondary signals from the second branched optical signal portion in the optical modulating device (458) under control of the control and/or monitoring signals (456) in the at least one repeater station so as to keep an optical carrier frequency of said further optical secondary signals to be transmitted equal to that of the optical secondary signals received in the at least one repeater station (40, 50) and so that the further optical secondary signals are interleaved by time-division or code-division multiplexing;
• wherein no optical carrier signals are generated in said at least one of said optical repeater station (40, 50).

A monitoring and/or control device in an optical repeater station for monitoring and/or control of transmission of message signals over an optical line, said monitoring and/or control device including

• means for receiving optical secondary signals together with the message signals in the optical repeater station;
• means (45) for generating further optical secondary signals to be transmitted from the optical repeater station (40,50) from the optical secondary signals received in the optical repeater station (40,50), said means (45) comprising a hybrid circuit (451) for splitting the received optical secondary signals to form a first branched optical signal portion and a second branched optical signal portion, an optical monitoring and/or control receiver (454) for generating control and/or monitoring signals (456) from the first branched optical signal portion and an optical modulating device (458) controllable by the control and/or monitoring signals (456);
• means for producing the further optical secondary signals from the second branched optical signal portion in the optical modulating device (458) under control of the control and/or monitoring signals (456), so that an optical carrier frequency of said further optical secondary signals transmitted over the optical line is equal to that of the optical secondary signals received in the at least one repeater station (40, 50) and so that the further optical secondary signals are interleaved by time-division or code-division multiplexing;
• wherein no optical carrier signals are generated in said at least one of said optical repeater station (40, 50).