Operator cut-in facility for time multiplex exchange - using central controller re-assigning time slots and connecting coder-decoder in parallel to other time slot

摘要

Two subscribers (TA,TB) are connected via a time-multiplex telephone exchange by the central controller assigning time slots to them on the data-bus (S). Separate time slots are used for the two directions. Speech signals are converted to and from PCM in the assigned time slots by peripheral units (AS) containing send and receive coder-decoders (CV,CR). If an operator (PL) wishes to tap the connection and talk to one subscriber (TB), the central controller reassigns (S1) the other subscriber's (TA) sending time slot the operator. It also connects (S2) the operator's coder-decoder in parallel with the other time slot. Thus the operator and one subscriber (TB) are in two-way communication. The other subscriber (TA) cannot speak to anyone but can still hear the first subscriber (TB). This scheme provides operator break-in facility without using special mixing units.