Abstract:
PURPOSE: A method of monitoring an amplified WDM(Wavelength Division Multiplexed) system using OTDR(Optical Time Domain Reflectometry) proceeding against transmission data is provided to reduce the impact of data losses and to amplify OTDR pulses without EDFA(In-line erbium Doped Fiber Amplifier). CONSTITUTION: In the method of monitoring an amplified WDM system, optical signals from optical transceivers(Tx1-TxN) go through a multiplexer(100) and an optical amplifier(110). And the signals are combined at a WDM coupler(120) and given as an incidence to a first-level optic-fiber span(130). The incidence optic signals go through, in turn, a first-level EDFA(140), a second-level optic-fiber span(132), a second-level EDFA(142), a third-level optic-fiber span(134) and a WDM isolator(122) and arrive at a receiver(RX). Meanwhile, an OTDR monitor(150) locates at the same level with the receiver(RX) sends OTDR pulses in the opposite direction of transmitted optic signals. Here, the first-level and second-level EDFAs(140,142) enables duplex transmission only for signals having the wavelength of through a change of the EDFA structure.