| 摘要 |
In a subscriber line interface circuit connected to a telephone line having a high potential wire and a low potential wire, an arrangement for generating a signal for determining the line voltage comprises means (7, 10, 11) for alternately charging a capacitor (6), by means of a first DC current, to a first voltage, and discharging the capacitor (6), by means of a second DC current, to a second voltage. Hereby, a sawtooth wave having an amplitude corresponding to the difference between the first and second voltages is produced. This sawtooth wave is converted to a pulse train related to the line voltage, from which the line voltage can be determined. |
