Combined speech and video transmission system - uses identification analyser to establish four-wire omnibus link

摘要

The transmission system enables both speech and video signals to be transmitted alternately between transmitting stations via four-wire circuits. Each transmitting unit (FUE) with its auxiliary unit (VDZ) can be connected via switching contacts (fg, fk) of a search/identification unit (SID) to a multiple cable (vl1, vl2). In addition to conference links, the transmitting units can be connected to a video omnibus transmission unit (TSU). Before the units are connected, an analyser (AW), operating in conjunction with a control unit (VDN), check the presence of an identification potential generated by each transmitting unit authorised to take part in the conference connection. The identification signal is produced in the auxiliary unit when interrogated.