| 摘要 |
PURPOSE:To reduce the line changeover time by providing a timer interrupting a switch drive signal for a prescribed time and giving a pseudo random signal to a transmission section after a prescribed time during the line changeover. CONSTITUTION:In adding a main signal to a transmission section 21 of a terminal station A and sending the signal in place of a test pulse, a CR circuit of a reception section 311 of a relay station B tries to take synchronization with the said signal and synchronizes with the signal after a time (t). Further, the frame synchronization is taken after the time (t), but the time is at the outside of the line changeover time, a switch drive signal from an operating frame synchronization circuit 312 of a timer 315 does not drive a switch 313. Thus, a pseudo random signal PN is not fed to a transmission section 314 but the said signal is fed. A relay station C takes a time for the frame synchronization after the time (t) similarly as the relay station B. The same processing is applied also to a terminal station D and the frame synchronizing signal is sent to a carrier terminal station through a line changeover device 6. Since the switches 313, 413 are not driven by timers 315, 415 during this period, no signal PN is fed to the transmission section and the time synchronously with the signal PN is saved. |
