Method and apparatus for implementing run length limited codes in partial response channels

An apparatus for encoding segments having a selected number of ordered bits of binary data, from a sequence of ordered bits of binary data into corresponding codewords, having a selected number of ordered bits of binary data, such that the sequence of ordered bits of binary data is encoded into a corresponding sequence of codewords, the apparatus comprising:

• receiver means for receiving the segments;
• separating means for separating the selected number of ordered bits of binary data of each segment into a corresponding first group and a corresponding second group;
• encoder mapping means for mapping each first group into a corresponding word having a selected number of ordered bits of binary data;
• and
• interleaving means for interleaving the bits of each corresponding second group with the selected number of ordered bits of binary data of each corresponding word to obtain codewords corresponding to the segments, such that (a) each codeword has no more than a first preselected number of consecutive zeros therein, (b) adjacent codewords in the sequence of codewords have no more than the first preselected number of consecutive zeros across the boundary therebetween, (c) each codeword comprises two subsequences, one subsequence consisting only of every other bit of the selected number of ordered bits of binary data of the codeword and another subsequence consisting only of the remaining bits with each of the subsequences having no more than a second preselected number of consecutive zeros therein, and (d) adjacent subsequences of codewords within the sequence of codewords have no more that the second preselected number of zeros across the boundary therebetween.