| 摘要 |
PURPOSE: To prevent the deterioration of signals caused by the variance of the light wavelength when the signals are received at a receiver station. CONSTITUTION: The light receivers 21 of a transmitter station are connected to the excess optical fiber terminals 20 of the optical multiplexers 14, and the noises mixed into the output of the receivers 21 are measured. Then the light wavelengths of light sources 13 of the transmitter stations 11 , 12 ... are adjusted in accordance with the measured noise levels so that these levels are reduced. When a noise measuring device 22 detects the noises, an alarm signal is outputted and returned to a modulator 12 of a transmitter station. Then the alarm signal is superposed on the signal sent from the signal source of the transmitter station and sent to a receiver station 2. At the station 2, the transmitter station that produced the alarm signal is identified and the light wavelength of the light source 13 or the identified transmitter station is controlled so that the noise levels are reduced. The noise signal detected by the device 22 is fed back to the source 13 of the transmitter station, and the wavelength adjusting circuit is controlled. Thus the light wavelength of the source 13 is automatically adjusted. |
