Patent ID: 7119721

Claim:
A method of converting a stream of databits of a binary information signal into a stream of databits of a constrained binary channel signal, wherein the stream of databits of the binary information signal is divided into n-bit information words, said information words being converted into m1-bit channel words in accordance with a channel code C1, or m2-bit channel words, in accordance with a channel code C2, where m1, m2 and n are integers for which it holds that m2>m1>n, wherein the m2-bit channel word is chosen from at least two m2-bit channel words, at least two of which have opposite parities, a concatenation of the m1-bit channel words and the m2-bit channel words complying with a runlength constraint of the binary channel signal, characterized in that the method comprises the repetitive and/or alternate steps of: selecting the m1-bit channel word from a set out of a plurality of sets of m1-bit channel words, each set comprising only m1-bit channel words having a beginning part out of a subset of beginning parts of the m1-bit channel words, each set being associated with a coding state of channel code C1, the coding state being established in dependence upon an end part of the preceding channel word, or: selecting the m2-bit channel word from a set out of a plurality of sets of m2-bit channel words, each set comprising only m2-bit channel words having a beginning part out of a subset of beginning parts of the m2-bit channel words belonging to said set, each set being associated with a coding state of channel code C2, the coding state being established in dependence upon an end part of the preceding channel word, the end parts of the m1-bit channel words in a coding state of channel code C1 and the beginning parts of the m2-bit channel words in a set of channel code C2 being arranged to comply with said runlength constraint.