An Experimental Electronically Controlled Automatic Switching System

This paper describes a laboratory experiment in automatic telephone switching systems. The investigation was conducted at the research level to gather valuable information and circuit techniques from a laboratory trial and not to evolve a system economically competitive with existing systems since the area of investigation is always broader and the results more general in character when the work is unfettered by economic restraints. Indeed, the results are not economically competitive. Purposes of the investigation were to determine what advantages may be derived from faster operation, largely through the use of electronic techniques, and to introduce and test some previously unexplored philosophies in switching and signaling. Some of the basic tools employed were dry-reed relays, mercury relays, multi-element cold cathode gas tubes, cold cathode gas diodes, and thermionic electron tubes. An experimental subscriber's telephone set, incorporating a preset dial mechanism with circuits for generating dialing signals of a new form, together with suitable signal receivers for the central office was designed as well as a novel type of switching network with its control circuits. A basic aim of the experiment was one-at-a-time operation within the central office. 443