| 摘要 |
PURPOSE:To economically monitor an alarm caused by a fault at a remote terminal station without newly performing capital investment by transferring the alarm between a main station and the terminal station through a main signal line in the case of transmission between two points in a small scale network. CONSTITUTION:A PCM signal sent from the main station is converted into a unipolar signal by a reception side bipolar/unipolar converting circuit 1, detected by a high-order group alarm (AIS) detection circuit 2 and inputted to a frame synchronizing circuit 3. In this case, the frame synchronism of the transmission line is taken, an error check circuit 4 and a counter station alarm detection circuit 5 detect transmission line error and step out of synchronism on the main station side, and the signal is separated into (n) channels by a separating circuit 6. On the transmission side, the PCM signals of (n) channels are multiplexed by a multiplexing circuit 7, an OR circuit 8 in a lump sends step out of cynchronization information, transmission line error information and various alarms to an inserting circuit and sends them to the transmission side. Next, the signal is passed through an inserting circuit 10, converted into a bipolar signal by a converting circuit 11 and sent to the main station. |
