| 摘要 |
PURPOSE:To test a transmission line only with a line for signal transmission without sending out a signal to the line all the time for maintaining a test state by providing a control circuit which allows signals to by-pass a signal regenerating circuit in a repeater. CONSTITUTION:A test start signal from a station is passed through a down circuit 10 and detected by a test start signal detecting circuit 1 to control the control circuit 2, thereby setting a switch 4, which is set at the side of the signal regenerating circuit 3 in the repeater to the side of a detour line 5. Consequently, the transmission line is considered as a couple of cables. A test end signal from the station is detected by a test end signal detecting circuit 6 to control a test end signal sending-back control circuit 7, thereby setting a switch 8 so that the test end signal is sent out to the side of an up circuit 11. A host repeater detects the test end signal from the low rank repeater by a test end signal detecting circuit 9 and the control circuit 2 is so controlled as to maintain the test state when the test end signal is detected or to control the switch 4 so that the test state is reset unless the test end signal is detected. The test state is thus reset successively from low rank repeaters. |
