| 摘要 |
PURPOSE:To exclude impedance mismatching at the insertion of a branch and error in a transmission line signal by using an optical branching and coupling element provided with a half mirror which transmits incident light and reflecting it to the direction at a right angle to the incident direction. CONSTITUTION:A signal outputted from, e.g., a terminal 31-2 is formed into packet at a node 30-2 and converted into an optical signal, and then outputted to optical fiber cables C2, D2 via a bidirectional optical branch inserting circuit 14-2. Its output signal is branched to other bidirectional optical branch insertion circuit and also received again by the node 30-2 via a branch line B2. A signal received by nodes other than the node 30-2 at the transmission side is thrown away or outputted to a corresponding terminal depending on the decoding of addressed information. The node 30-2 at the transmission side compares whether or not the returned signal is identical to the transmitted signal so as to discriminate the presence of error, and when an error exists, the same signal is transmitted again after a proper time. |
