| 摘要 |
PURPOSE:To monitor a repeater further than a branch insertion type terminal station or a PCM terminal station at the one side of a transmission line, by providing newly a means which performs a direct connection between both U-B and B-U converting circuits by the detection of a pulse trio signal. CONSTITUTION:With a bipolar PCM serving as a normal data signal, the plus and minus polarity emerge alternately for the output of a B-U converter 101. On the contray, the combinations of plus-minus-plus or minus-plus-minus pulses are repeated with a pulse trio signal during a test. A deciding circuit 104 makes use of this regularity to detect a pulse trio signal during a test and then switches a switch 105 to the upper side as shown in the diagram. Then a connection is given so that the output of the circuit 101 is fed to a U-B converter 102. Thus a pulse trio similar to an input PCM-R is obtained as an output PCM-S. This enables a remote test with no effect received from a branch insertion type terminal station 103. |
