Digital signalling system

Claim 1

A digital data transmission system for transmitting character-manifesting signals from a transmitting station to a receiving station, said system comprising: a pulse train generator located at said transmitting station for selectively generating any one of a plurality of charactermanifesting pulse train signals, said pulse train generatOr including, a pulse source producing a plurality of pulses occurring in serial order in a certain length time interval, a plurality of separate switching means each having respective open and closed switch conditions and first and second terminals, preprogrammed means having an input coupled to said source of pulses and having a plurality of outputs each of which is individually coupled to the first terminal of a different one of said switching means for distributing successive ones of said plurality of pulses among said switching means in accordance with the program of said preprogrammed means, and pulse combining means having a plurality of separate inputs each individually coupled to the second terminal of a different one of said switching means, and having a single output at which appears said pulse train signal, whereby said pulse train signal consists of that number of pulses occurring during said time interval equal to the sum of pulses distributed to said first terminals of only those switching means which are in their closed switch condition during the length of said time interval, character selection control means located at said transmitting station and coupled to said pulse train generator for controlling the selection of that one of said plurality of pulse train signals which is generated for said certain length time interval in accordance with the particular one of a plurality of characters which is then to be transmitted, transmission means for transmitting said selected pulse train signal from said transmitting station to said receiving station, and counting means located at said receiving station and operative over a receiving time interval substantially equal in length to said certain length time interval, said counting means being responsive to the receipt of said selected pulse train signal at said receiving station being applied as an input thereto for producing an output signal therefrom manifesting the number of pulses received during said received time interval, whereby the transmitted character is uniquely defined by said output signal.