| 摘要 |
<p>PURPOSE:To attain simple loopback test and to reduce the investment of installation by sending a control signal to close a line of a voice band of an attended station from an unattended station and a line test signal and allowing the attended station side to measure the test signal. CONSTITUTION:A signal generator 1 sends a loopback signal of a frequency on a voice practical band to an unattended station A. A receiver 2 has a band pass filter of a narrow band and receives only a frequency signal corresponding to the loopback signal decided in advance. In case of receiving the loopback signal, a switch 3 is subject to switch control and lines a, b are closed as shown is broken lines in figure to attain the loopback state. Then a test signal is sent to the line (a) from the signal generator 1 and the test signal from the line (b) is measured by a measuring device 4 to conduct the test of the voice band line cable 5.</p> |
