| 摘要 |
PURPOSE:To prevent the affect on an exchange system device by detecting out of synchronism of a transmission line and changing over the transmission line before the exchange system is changed over when out-of-synchronism of the transmission line occurs. CONSTITUTION:If a transmission line fault such as out-of-synchronism occurs in the transmission line 2, a transmission line switching signal is transmitted to a changeover indicating circuit 103 from synchronism pattern transmission and synchronism detecting circuits 101 and 102. Switching circuits 104 and 105 provided to the transmission line 2 change over the transmission line 2 by the indication of the changeover indicating circuit 103. Since only the transmission line is changed over without changeover of the exchange system device, the exchange system device regards it as a momentary interruption of the transmission line and the communication is continued. |
