| 摘要 |
<p>If in a connection between two subscriber sets (or more as in conference circuits) too much attenuation occurs, amplifiers are provided in the four-wire line. The gain of these amplifiers is determined by the direction in which the high (net) energy flows in the two-wire connection to the subscriber set. The disadvantage of direction detection in the two-wire portion and changing-over the gain in the four-wire portions, namely the fact that additional and long signal lines are required is obviated by the measure in accordance with the invention by having that detection also occur in the four-wire portion.
<??>In conference circuits, unwanted simultaneous amplification of signals coming from different subscriber sets is prevented from occurring by attenuating (14, 15) the signals, coming from the four-wire line for the detection circuit, for one communication direction and by amplifying (15, 14) these signals for the other communication direction. </p> |
