| 摘要 |
<p>In order to avoid separately adapted amplifiers for the phantom quad line and a replacement line in case of repair or replacement of cable cores, a buffer switch arrangement is provided for the quad line transfer step switch (LU) which contains eight symmetrical transformer coils. Each quad connection (11,12,13,14) is preceded by a symmetrical transfer coupling (71,81). Similarly, the terminal pairs (31,32,33,34) are symmetrically coupled to the incoming quad lines (31',32',33',34') via transformers (73/83, and 71/81 respectively). It is important that the centre tap of the windings of the corresponding incoming and outgoing coil pairs are connected with each other galvanically. If the phantom circuit is used for the transmission of 2 megabit signals, it is not advisable to use the main line for carrier frequencies above 556 kHz. Nevertheless it is possible to do this by the inclusion of a reject filter between the unit and the transmission cable of the outgoing quad lines.</p> |
