| 摘要 |
PROBLEM TO BE SOLVED: To compensate the temperature dependence of a communication transmission band and to prevent the degradation of transmission quality by measuring the change in the wavelength band of the light outputted to respective branched optical fibers from a wavelength selection type optical branching device and controlling the wavelength of outputted communication light, based on the measured result. SOLUTION: Pulse-monitoring light which differs from the wavelength of communication light is outputted from an optical pulse testing device 9, and the maximum intensity of returning light from a specified branched optical fiber is measured in the optical pulse testing device 9. From the difference between the monitoring wavelength of the maximum intensity at the time and the reference wavelength of the monitoring channel of a subscriber optical branching device 4 recognized beforehand on the side of a CPU/wavelength controller 10, a drift amount is obtained. Then, the drift amount of a communication channel is estimated, and the drift amount of the communication channel of an intra-station optical branching device 4' and the communication wavelength of respective transmitter-receivers 2-1 to 2-n is compensated. Thus, the transmission loss of the subscriber optical branching device 4 is maintained at a minimum, and the degradation of the transmission loss can be prevented before hand. |
