2. The combination in accordance with claim 1 wherein said multi-stage bit generator has an odd number of stages whereby an odd number of bits is contained in each repeating sequence.
1. In a data communications system, apparatus for transmitting digital data and control signals on a common channel intermixed without restriction as to the format of data transmitted comprising; a multi-stage bit generator for generating a train of bits having a repeating sequence; means for combining data to be transmitted with the output of said bit generator to modify said data as a function of said bit sequence; a control code detector for detecting a predetermined number of bit combinations indicative of control information; means for applying the output of said combining means to the input of said control code detector; means responsive to the detection of a control code in said output for modifying said output; and means for selectively introducing control codes and the output of said last means into a transmission channel.