Coded multiple frequency signal exchange circuit - has transmitter for AF signals in peripheral control unit connected by multiplex line to connecting circuits

摘要

The signals are exchanged over connecting lines between centrally controlled telephone exchanges. The system ensures that connecting circuits transmitting the AF signals are regulated by peripheral control units connected to the central control unit. Each line bunch of a peripheral control unit has a transmitter for the coded multiple frequency AF signals. It is connected through a common multiplex line to the connecting circuits belonging to the line bunch. A large number of telephones may be connected in the network.