METHOD AND SYSTEM FOR MONITORING OPTICAL LINE, AND OPTICAL LINE MONITORING DEVICE AND PROGRAM THEREOF

PROBLEM TO BE SOLVED: To provide an optical line monitoring method capable of monitoring an optical line in a wavelength multiplex optical transmission system with high accuracy, to provide an optical line monitoring system, and to provide an optical line monitoring device and a program thereof at low cost. SOLUTION: Transmission power Io(λi) of each wavelength light multiplexed to wavelength multiplex light 11 in an optical fiber 9 to be monitored, normal return light power SA (λi, Δxi), and abnormal return light power SB (λi, Δxi) are measured. From each measurement value, return light power S' is calculated from a formula 7, with an abnormal loss position Δxi and an abnormal loss coefficient A (Δxi) as parameters, thus determining the abnormal loss position Δxi and the abnormal loss coefficent A(Δxi), where the value is brought closer to the abnormal return light power SB (λi, Δxi). COPYRIGHT: (C)2009,JPO&INPIT