| 摘要 |
PCT No. PCT/SE83/00242 Sec. 371 Date Mar. 6, 1984 Sec. 102(e) Date Mar. 6, 1984 PCT Filed Jun. 14, 1983 PCT Pub. No. WO84/00459 PCT Pub. Date Feb. 2, 1984.A method in current feed to a subscriber telephone from a telephone exchange in which there is arranged a voltage source (11). A differential amplifier (1) senses the potential difference between the terminals of the voltage source (11), and after low pass filtering (2) a reference voltage (UREF) is added (3). The thus-obtained sum voltage is allowed to constitute the reference value in the system. The arithmetical mean value of the terminal potentials of the voltage source is utilized as a corresponding actual value. The difference between these reference and actual values is allowed to control a current tap in equal phase from both terminals of the voltage source. |
