Basic principles of the varioplex telegraph

A new kind of channel-sequencing system allots the full capacity of a telegraph circuit to the busy channels alone. A busy channel cuts itself out of its sequential position by becoming idle but may re-enter the sequence at will by offering one letter for transmission. Entry, mixing, and exit are accomplished by electromechanical control of standard start-stop and multiplex printing telegraph apparatus. Special signal or code combinations are used to denote changes in the pattern of subchannels cut in, and to act as a check on correct distribution. For greater efficiency, ordinary message letters, by a new method, may be interspersed among successive elements of switching combinations, and the cascading of combinations is also employed. Dummy channels, high-speed receivers, and other devices may be used to prevent or utilize unusual channel speeds. Varioplex systems may be repeatered either by subchannel storage or by storage involving several subchannels handled as a unit.