| 摘要 |
The subject of the invention is a communications device connected in parallel with at least one item of communications apparatus on a transmission line (L1, L2). The device and the apparatus conform to a given template in terms of DC components. The device in accordance with the invention is characterized in that it comprises means (18, R1, R2, R3, D5, DZ) setting the operating point (X) in terms of DC component of the said device alone outside regions of the said template where the DC component of the current may be zero, means (R2, D6, D7, R4, 19, 20) of determining the DC component of the current flowing in the said device, means (20) of detecting a variation in the said DC current component. The invention applies particularly in the field of communication via the switched telephone network.
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