| 摘要 |
PURPOSE:To realize a change-over system between a normally used transmission line and a stand-by transmission line which automatically switches the normally used line to the stand-by line when the normally used line is in troubles, by installing a means which detects interruptions of input signals. CONSTITUTION:When a circuit trouble occurs in the A-system trnsmission line LA among A- and B-system transmissione lines LA and LB connected to a change-over switch S1 of a communication station, an integrating circuit (abef) of a change-over controlling section (abe) works and an integral output INT is lowered after a prescribed time. At this time, an one-side differentiating circuit (abeg) works and its differential output TRG is given to a flip flop circuit FF as a trigger pulse. Since the B-system transmission line is under a normal condition, only a B-system remote change-over signal BCH is supplied to the flip flop circuit FF as a reset signal, and the flip flop circuit is set to a reset condition. Therefore, the change-over switch S1 is switched to the B-system transmission line which works as a stand-by transmission line. |
