| 摘要 |
PURPOSE:To receive and detect a control signal from a station side through a communication line so as to form a repeater bypass and also to prevent the line balance of a signal reception section detecting the control signal from being lost to the communication line by omitting a control line for repeater bypass. CONSTITUTION:A control voltage for test measurement of the communication lines LA1, LB1, LA2 and LB2 transmitted from the station side 10 passes through a gate circuit 43 and detected by a voltage limit circuit 44. Then a DC-AC converting circuit 45 is driven by a detected signal and a relay of a regulating circuit 46 is activated by the converted output. Switches S1-S4 of the 1st and 2nd switching circuits 42A, 42B are thrown to the brake position by an output of the regulating circuit 46, allowing to constitute a circuit bypassing the repeater 20. Thus, the station side 10 and the terminal station side 30 are coupled directly without the communication lines LA1, LB1, LA2 and LB2 without intervention of the repeater 20. Even if a normal communication signal is incoming, since a gate circuit 43 showning a high impedance in comparison with the impendance of the communication lines, no hindrance takes place. |
