Frequency multiplexed private telephone exchange - has control containing transmitters and receivers for control signals

摘要

The frequency multiplexed private telephone exchange has carrier frequency multiplex lines and a control for the modulators and demodulators. The control is coupled to the multiplex line and contains a monitoring circuit, a signal receiver, a signal transmitter, a control circuit, a memory and a frequency generator. The monitor and the receiver are coupled to give carrier frequency channels. The control circuit passes control signals to the lines via the transmitter and receives control signals from the lines via the receiver.