Analogue telemetry system and method for fault detection in optical transmission systems

摘要

An analogue telemetry system/method provides fault location in an optical transmission system including optical fibre amplifiers. Each amplifier has a respective optical pump source including an AGC loop around the optical amplifier's fibre. Spontaneous emission from the optical fibre amplifier is detected and employed to drive the respective pump source to maintain the amplifier output at a predetermined level. A supervisory tone is applied at the transmission end of the system and its presence/absence detected at each amplifier. In the event of "absence", a respective distress tone is applied at the relevant amplifier. At the receiver end of the system, the supervisory tone is sought and in the absence, the number of distress tones, if any present, is counted and the position of the fault is thus determined.