| 摘要 |
<p>PROBLEM TO BE SOLVED: To shorten measurement time and to maintain measurement accuracy by identifying the presence/absence of a high time constant circuit and deciding secondary discharging time and maximum charging time suitable for a time constant. SOLUTION: When a measurement instruction is issued from a host device 2, a subscriber's line 3 is connected to a discharging circuit 14 by the changeover of a selector 18 and a primary discharging processing is performed. When the discharging processing is ended, the subscriber's line 3 is reconnected from the discharging circuit 14 to a high impedance voltmeter 11 by the changeover of the selector 18. Then, a primary voltage is measured by the high impedance voltmeter 11. Since the measured voltage is an analog signal, it is converted into a digital signal in an A/D converter 16, sampled at a high speed and computed in a DSP 17. Then, the subscriber's line 3 is released by the selector 18. Then, since the remaining charge of the high time constant circuit 4 is charged to the subscriber's line 3 or a terminal 5 by waiting for prescribed open time, a measured voltage is stabilized in the next secondary voltage measurement.</p> |
