Rural automatic exchange with electronic control circuits

The paper describes a new type of non-register two-stage rural exchange for a maximum of 1000 subscribers. The control circuits are all-electronic, while the speech network is composed of crossbar switches. Further characteristics are as follows: The control circuits (electronic marker) are built up of transistors, cold-cathode tubes and diodes. For an outgoing call, subscriber-dialled digits are received in a register at the main exchange. Establishment of all other calls (incoming and local) is controlled by the main exchange via a separate control line. The control line may serve several rural exchanges. Trunk line connections of incoming and outgoing trunk calls are established in the direction from the rural to the main exchange. The first of the two stages of the rural exchange may work separately as a line connector with remote control over the control line. The exchange is suitable for centralized subscriber metering at the main exchange. However, subscriber meters located at the rural exchange may also be used. The exchange is now in the shape of a few line connectors in actual service at various locations in the Jutland network. Within a year about 25 line connectors will be installed as part of the automation of the present manual exchanges. The first complete rural exchanges are expected to be in service in 1962.