| 摘要 |
PURPOSE: To confirm the normality of a standby system line (inactive line) at system changeover. CONSTITUTION: The system is provided with main signal line side termination circuits 5a, 5b sending/receiving a main signal, maintenance signal line side termination circuits 7a, 7b sending/receiving a maintenance signal to detect the normality of a standby line, phase adjustment circuits 6a, 6b receiving either the main signal or the maintenance signal to adjust its phase, and selection circuits 8a, 8b, the main signal is selected in the operating state and usual communication is conducted via an active line, the maintenance signal is selected in the inoperating state to send/receive the maintenance signal via the standby line thereby detecting the normality of the standby line based on the result of transmission reception. As a result, the propriety of the standby line is detected before system changeover to block the changeover to an abnormal line. |
