| 摘要 |
<p>In a mains-type house-line or house-communication system operating by the dialogue method, the number of connectable transmission/receiving sets should be as large as possible. This can be achieved if the receiving circuit of a transmission/receiving set requires only a small part of the transmission power emitted. According to the invention, in synchronisation with the switching of the transmission from transmission to reception and vice-versa, a switching is effected of the coupling impedance linked with the mains line. This is designed is such a way that a lower-ohm transmission output impedance and a higher-ohm receiving input impedance is produced. The circuit arrangement developed for implementation of the process is so designed that a repeater (Ü1) couples both a transmission circuit (1) and also a reception circuit (2) to the leads of a network. Connected in series with the secondary winding (W2) of the repeater (Ü1) is a controllable switch (T3) which is short-circuited during the transmission mode and thus is low-ohmic, and during the receiving mode is open and thus high-ohmic.</p> |
