An experimental electronic telephone exchange on a time-division basis

The paper describes an electronic telephone exchange based on time-division techniques but using a common pulse supply circuit for its controls and speech-path carrier pulses. A `semi-highway¿ switching system is used. Each subscriber is allotted a fixed pulse of a train of pulses. Connections between a calling and called subscriber are made either by shifting the phase of the pulse at the outgoing side of connection or by the use of audio links. Since the control and memory circuits are connected at the outgoing side of the system the number of them is reduced and concentrated. An outline of the system is given and its control circuits, switching network and set-up procedure are briefly explained. The traffic-handling behaviour of system is considered and the method of determining the number of channels in a highway is indicated. The first model based on these principles was built by the authors in March, 1958. It was on a smaller scale than the model described, which was completed in March, 1960, and is at present under test.