| 摘要 |
PURPOSE:To measure a communication line up to its maximum distance permitted to communication by setting a test use folding path under the state of an equalizer is connected to the communication line. CONSTITUTION:When a DC power supply DC is applied between midpoints of relay coils REP1 and REP2 in an exchange station CO, a relay RL connected between midpoints of relay coils REP3 and REP4 in a line terminator DSU', an output side of the equalizer EQ and an input side of a code converter UBC are connected to set the test use reflected path. A code generator CG is connected to an outgoing line DL in this state, and a mark code of bipolar form transmitted to a terminal device in the communication state is transmitted as a test code. In case connecting a level measuring device LM to an incoming line UL, the test code transmitted from the code generator CG is transmitted to the EQ in the DSU', and after the code is converted into the unipolar form, the result is transmitted to the UBC via the test use reflected path, and after the result is converted into the bipolar form by the UBC, the code is transmitted to the LM via the UL and the transfer characteristic of the DL and UL is tested. |
