| 摘要 |
PROBLEM TO BE SOLVED: To suppress influences upon a transmission feature of increase/decrease of the number of wavelengths accompanying the switching of redundancy system by making a gain of a light amplifying repeater smaller while an active channel of an active system which is faulted is connected to a standby system light terminal station device at the time of faulty of the active system. SOLUTION: When a light level of a light wavelength λ1 is lowered or enters a quenching state due to failure, the light wavelengths other than λ1 are excessively amplified in light outputs of light amplifying repeaters 29a to 29n, transmission features of λ2 to λ5 are deteriorated by being shifted from a state of line design and a normal communication state cannot be confirmed. Thus, in this light redundancy switching method, it is controlled so that gains of the light amplifying repeaters 29a to 29n are made smaller and the transmission features of the λ2 to λ5 are maintained in a normal state. In this way, since the gains of the light amplifying repeaters 29a to 29n are made smaller at the time of faulty of the active system, normality of a standby system can be normally confirmed and, at the same time, influences upon the transmission features by reduction of the number of wavelengths for emitting light can be suppressed. |
