An apparatus for generating a data signal comprises a processing circuit configured to generate the data signal, the data signal comprising a sequence of a first signal edge of a first type, a second signal edge of a second type, and a third signal edge of the first type, the first signal edge and the second signal edge being separated by a first time period corresponding to first data to be transmitted, and the second signal edge and the third signal edge being separated by a second time period corresponding to second data to be transmitted. An output interface circuit is configured to output the data signal.