A 24-Channel Pulse-Code- Modulation Junction Carrier System

Presently the British Post Office orders and install 24-circuit pulse-code-modulation systems in large quantities for the junction network. The traffic carried is between a local exchange and a group switching center, local and tendem, and between local exchanges; often these requirements are combined in one traffic route. The basic principles of pulse-code modulation are now known, and papers have appeared describing the system technique. Mostly they have dealt with contemplated experimental development or field-trial systems, the major exception being a series of articles on the Bell Telephone System T1 carrier that has been in regular commercial use for several years. This paper describes a new pulse-code-modulation system now in high volume production, which was the first of its kind to be installed on a large scale for regular use in the United Kingdom telecommunications network.