DEVICE FOR ENCODING/DECODING N-BIT SOURCE WORDS INTO CORRESPONDING M-BIT CHANNEL WORDS, AND VICE VERSA

摘要

A device is disclosed for encoding a stream of databits of a binary source signal (S) into a stream of databits of a binary channel signal (C), wherein the bitstream of the source signal is divided into n-bit source words (x1, x2), which device comprises converting means (CM) adapted to convert said source words into corresponding m-bit channel words (y1, y2, y3). The converting means (CM) are further adapted to convert n-bit source words into corresponding m-bit channel words, such that the conversion for each n-bit source word is parity preserving (table I) (Fig. 1). The relations hold that mn1, p1, and that p can vary. Preferably, m = n + 1. The device is adapted to convert the 8-bit bitsequence '00010001' in the source signal into the 12-bit bitsequence '100010010010' and to convert the 8-bit bitsequence '10010001' into the 12-bit bitsequence '000010010010', in order to limit the repeated minimum transition runlength in the channel signal. Also other 8-bit sequences require a specific encoding into 12-bit bitsequences in order to limit the kconstraint of the channel signal to 7. Further, a decoding device is disclosed for decoding the channel signal obtained by means of the encoding device.