Superposed signalling over telephone lines in electronic exchanges - uses simultaneous transmission of connection build-up and fault signals

摘要

Translations (UE1, UE2) at the ends of the transmission line have a first (E1, E3) and a second (E2, E4) receiver, a constant current source (K1, K2) and a logic circuit (V1, V2). When a transmission potential is applied, two receivers (E1, E2) are connected in the outgoing translation (e.g UE1) and one receiver (E3) in the incoming translation (e.g UE2). After a specified testing time one receiver (E2) in the outgoing translation (UE1) is disconnected by an opposite potential (S2). Criteria on the state of connection build-up and of the transmission line is sent by connection together of receivers (E1, E2; E3, E4) in each translation during the testing time.