A 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 data bits of a binary source signal (S) into a stream of data bits of a binary channel signal (C1), wherein the bit stream of the source signal is divided into n-bit source words (x1, x2), which device comprises converting means (LC) adapted to convert said source words into corresponding m-bit channel words (y1, y2, y3). Each n-bit source word together with another n-bit source word forms a pair of source words. The values of the n-bit source words differ only in the value of the bit in the qth bit position, q being a constant. The pairs of source words is divided into a first part of pairs and a remaining part of pairs. The converting means (LC) are further adapted to convert n-bit source words belonging to the first part of pairs into corresponding m-bit channel words, in such a manner that the conversion for each of said n-bit source words is parity preserving, and to convert n-bit source words belonging to the remaining part of pairs into corresponding m-bit channel words, in such a manner that the conversion for each of said n-bit source words is parity inverting (Table I) (Fig. 1). Furthermore, a decoding device is disclosed for decoding the channel signal obtained by means of the encoding device.