| 摘要 |
A communication device connected in parallel to at least one communication apparatus via a transmission line (L1, L2). The device and the apparatus comply with a given DC component envelope. Said device is characterised in that it includes means (18, R1, R2, R3, D5, DZ) that place the DC component operating point (X) of the device alone outside the areas of the envelope where the DC current component may be zero, means (R2, D6, D7, R4, 19, 20) for determining the DC component of the current flowing through said device, and means (20) for sensing a change in said DC current component. The device is particularly useful in the field of switched telephone network communication. |
