| 摘要 |
PURPOSE:To prevent the intermittent state of an optical signal at changeover state from taking place nearly by controlling an optical switch for a time when the output of a standby output circuit is stable at the changeover of an output circuit and extracting other output of an active output circuit. CONSTITUTION:While an optical signal output circuit 5 of an active optical signal output circuit group 1 is in use, when an electric signal is inputted from an input terminal 10, the signal is inputted to the circuit 5 through signal distributers 3, 7. After the signal is converted into an optical signal by the circuit 5, the signal is sent from an output terminal 11 through an optical switch a and an optical coupler 4. When the circuit 5 is faulty, the condition switched to the standby signal output circuit 2 is satisfied and switched to the circuit 2 via a control circuit 9, the cold standby state is released in the circuit 9 to activate the circuit 2 and in observing the transition being in the stable state at the terminal 11, the intermittent state is detected in the optical signal. The circuit 2 is controlled to avoid it and the switch 8 is controlled once to extract the optical output of the optical signal output circuit 6 for a time when the output is stable. |
