Apparatus and method for recording and recovering a binary symbol sequence using an intermediate step of converting the binary sequence into a ternary sequence

摘要

The present invention relates to apparatus for recording representations of a binary symbol sequence which comprises conversion means (1) for converting the binary symbol sequence into a ternary symbol sequence, and recording means (3, 5, 7) for recording representations of the ternary symbol sequence. In accordance with the invention, the recording apparatus is characterised in that the conversion means comprises mapping means for mapping the binary symbol sequence into a direction constrained run length limited ternary symbol sequence, and the recording means comprises means for recording the ternary symbol sequence as selected recording levels with half transitions and full transitions between recording levels in such a way that each half transition is followed by another half transition of the same polarity.;The present invention also relates to a method of recording representations of a binary symbol sequence utilising recording apparatus as above.;The invention further relates to a combination of recording apparatus as above with means (11 to 16) for recovering the binary symbol sequence from the recorded representations, and to a combination of a method of recording as above with a method of recovering the binary symbol sequence from the recorded representations.