| 摘要 |
PURPOSE:To switch a line while the quality of a transmission signal is kept by starting the transmission of a standby line when the quality of the transmission signal of an active line is degraded and switching the line when synchronization is taken. CONSTITUTION:When a bit error rate reaches a prescribed rate or above, as soon as a line switching signal is sent to a line switching device 10 and a frame synchronization detector 9, the signal transmission in a standby line is started. Then the detector 9 implements frame synchronization based on a transmission signal sent through the standby line and after the frame synchronization in the standby line is confirmed, the switching device 10 is used to switch the line. Since the active line and the standby line are switched between a transmission frame and a frequency, the active and standby lines are switched without causing error correction disabling state of the signal caused when the switching is implemented in the frame of the transmission signal. |
