| 摘要 |
PURPOSE:To quicken pull-in synchronization by transmitting continuously a synchronizing signal at switching of lines. CONSTITUTION:When both transmitters DAS, DBS are normal, the transmitter DAS transmits data to a line A via a switching circuit SWA and the transmitter DBS transmits data to a line B via a switching circuit SWB cyclicly. If a failure occurs in the transmitter DAS, a switching control signal is inputted to the circuit SWA so as to be switched and the data from the transmitter DBS is transmitted to the line A. In this case, a status change detecting circuit DET1 detects the switching, inputs a detecting signal to the transmitter DBS and when the transmitter DBS receives this detecting signal, the synchronizing signal is transmitted continuously. If a failure occurs in the transmitter DBS, the transmitter DAS performs the similar operation. Further, if normal data are not received at a receiving side because of a failure of the line or the like, the data are received from the other system by the switching circuit. |
