| 摘要 |
<p>PURPOSE:To simplify the constitution of a subscriber's circuit, and to eliminate sufficiently an in-phase noise using a semiconductor element, by providing a pair of current supplying circuits for supplying a current to a pair of subscriber's lines, a current-voltage converting circuit, and an in-phase voltage detecting and controlling circuit, etc. CONSTITUTION:A current is supplied to a subscriber's line 2 having a pair of subscriber's lines A, B from a pair of current supplying circuits 6, 7, converted to a signal current on the subscriber's lines A, B by a voltage-current converting circuit 5, and the sum current is fetched. The sum current from this circuit 5 is made to flow to a circuit network 9, and voltage being proportional to an in-phase portion of the signal on the subscriber's lines A, B is generated. Basing on the voltage being proportional to the in-phase portion of the signal on the subscriber's line A, B from this circuit network 9, the current supplying circuits 6, 7 are controlled from the in-phase voltage detecting and controlling circuit 8. In this way, an in-phase noise eliminating circuit is mainly constituted of a semiconductor element, and the in-phase noise is eliminated sufficiently by a simple constitution.</p> |
