LIGHT AMPLIFICATION RELAY TRANSMISSION SYSTEM

摘要

PURPOSE:To supervise the ratio of signal to noise of a repeater by detecting both a main signal component and a noise signal component from a signal flowing through an optical transmission line, and informing the face to a terminal station by superimposing it on the signal flowing through the optical transmission line while a system executes ordinary service. CONSTITUTION:An electrical signal in correspondence to the photoelectric power of only main signal light is outputted from a receiver 28, and the electrical signal in correspondence to the photoelectric power of only a noise component from a receiver 29. A supervisory circuit 30 receives a supervisory control signal from the output of an optical coupler 25, and outputs the intensity of the main signal light and that of the noise component to a supervisory response signal superposition circuit 33 as a supervisory response signal when the fact that the signal designates an own repeater is detected. The circuit 33 outputs the supervisory response signal to an optical fiber 304 by superimposing on the main signal on a downstream line. The circuit 33 is constituted by modulating the exciting light source of a light amplifier 32 by the supervisory response signal, and superimposing intensity modulation on the main signal.