| 摘要 |
PURPOSE:To improve the transmission efficiency by using a 1st wavelength for an optical signal from a management station to a terminal station, using the 2nd wavelength for an optical signal from a terminal station to the management station and processing a frame of the optical signal sent from the management station. CONSTITUTION:The management station A is provided with an optical transmitter OSA sending an optical signal with a 1st wavelength lambda1 and an optical receiver ORA receiving an optical signal of the 2nd wavelength lambda2. Terminal stations B-D are provided respectively with optical branching confluence devices OTB- OTD coupled with an optical loop bus OB, optical receivers ORB-ORD and optical transmitters OSB-OSD. Through the constitution above, an optical request signal from the station A to the stations B-D uses the wavelength lambda1 and the optical reply signal from the stations B-D to the station A uses the wavelength lambda2. Thus, even when the bus OB is used in common, both the signals can be identified. Moreover, the station A processes the optical request signal as a frame and sends the optical reply signal for a definite period assigned to the stations B-D by a prescribed time each in each frame. Thus, no guard time is required and the transmission efficiency is improved. |
