Patent ID: 6639525
Filing Date: 2003-10-28
Classification: G11B,H03M

Abstract:
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, some of the information words being converted into m1-bit channel words in accordance with a channel code C1, and others being converted into 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 alternative m2-bit channel words, at least two of which have opposite parities, the m1-bit channel words and the m2-bit channel words being concatenated to form the channel signal complying with a runlength constraint,the conversion into m1-bit channel words includes 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 a preceding channel word, the conversion into m2-bit channel words includes 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 a preceding channel word, and the end parts of the m1-bit channel words in a coding stare 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.