Abstract: The method of controlling and/or monitoring an optical transmission of message signals over an optical line in a repeater station includes providing a device (45) for generating further optical secondary signals from the received optical secondary signals without generating a stable optical carrier signal for the secondary signals in the device (45). This device (45) includes 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.

Abstract: The invention relates to an optical communication-transmitting system for transmitting at least one useful signal with a high bit rate, which has intermediate repeaters (ZV.sub.1 -ZV.sub.n) with optical fiber amplifiers (OV.sub.ss, OV.sub.1 -OV.sub.n, OV.sub.es) and which uses at least one additional signal of a low bit rate, for example for monitoring the intermediate repeater. For a transmission system requiring small outlay, the additional signal is transmitted on a wide band in comparison to the useful signal, for example by means of luminescence diodes (S.sub.ss, S.sub.1 -S.sub.n) and is amplified by the fiber amplifiers (OV.sub.ss, OV.sub.1 -OV.sub.n, OV.sub.es) in the same manner as the useful signal. For transmitting and receiving the additional signal, a transmitter (S.sub.1) is preferably disposed in an intermediate receiver (ZV.sub.1) upstream of the fiber amplifier (OV.sub.1) and a receiver preferably downstream thereof.

Abstract: In an overvoltage protection circuit for an amplifier inserted in series between lengths of a signal transmission line, the line including a ground path and the amplifier being supplied with operating power via the transmission line and including power supply inputs conductively connected to the transmission line lengths via a current supply filter, there is provided: one single overvoltage arrester for providing coarse overvoltage protection connected between the ground path and one of the power supply inputs, and lowpass filters connected between the arrester and each transmission line length.