| 摘要 |
PURPOSE:To determine the capacitance of a subscriber line accurately by substitution of electric charge for a reference capacitance varying a voltage to be applied thereto calculate the line capacitance depending on the difference in the voltage. CONSTITUTION:An electric charge of a reference capacitance CS discharged through a (w) contact. Then, an (x) contact is operated to charge a line capacitance with a power source E1. Then, a Y relay is operated to return the electric charge accumulated in a capacitance C to the CS to measure a voltage e1. Then, the (w) contact is operated to discharge the electric charge returned to the reference capacitance CS. A (z) contact is operated to charge the capacitance C with the E2. The subsequent operation measures a voltage e2 returned to the reference capacitance CS as the operation with the voltage of the E1 does. Then, the line capacitance C is calculated by formulaI. With such an arrangement, effect of a rectifier on the line can be ignored thereby enabling the line capacitance accurately. |
