Multiplex Telegraphy

a method of sequential time-division multiplexing of a communications line. The principle of multiplex telegraphy consists in the automatic sequential connection of the telegraph transmitters or receivers of one station to the corresponding transmitters or receivers of another station for short time intervals over a communications line (channel) by means of mechanical or electronic distributor switches. The connection rate is determined by the number of transmitters or receivers in a station. Multiplex telegraphy with mechanical distributor switches was used until the early 1960’s; in wire communications it was gradually replaced by telegraphy methods using single-operation start-stop apparatus as a result of the introduction of frequency telegraphy in the 1930’s. Multiplex telegraphy with electronic distributor switches came into use in the mid-1960’s as a means of providing time-division multiplexing for telephone channels and as a way of transmitting telegrams through radio channels.