Patent ID: 6469645
Filing Date: 2002-10-22
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, said method comprising converting each n-bit information word of a binary information signal into a channel word such that the binary channel signal includes a sequence of channel words:wherein each said channel word is selected from the group consisting of an m1-bit channel word in accordance with a channel code C1 and an m2-bit channel word in accordance with a channel code C2, wherein n, m1, and m2 are positive integers such that m2>m1>n, wherein at least two of said m2-bit channel words have opposite parities, wherein said channel words are concatenated such that said sequence of channel words comprises said concatenated channel words, wherein said concatenated channel words comprise concatenated m1-bit channel words and m2-bit channel words, wherein said concatenated m1-bit channel words and m2-bit channel words comply with a runlength constraint of the binary channel signal, wherein converting said n-bit information word into said m1-bit channel word comprises selecting a set of m1-bit channel words from a plurality of sets of m1-bit channel words followed by selecting said m1-bit channel word from said set of m1-bit channel words, each set of m1-bit channel words being associated with a coding state of said channel code C1, said coding state of said channel code C1 being established in dependence upon an end part of the preceding channel word in said sequence of channel words, wherein converting said information word into said m2-bit channel word comprises selecting a set of m2-bit channel words from a plurality of sets of m2-bit channel words followed by selecting said m1-bit channel word from said set of m2-bit channel words, each set of m2-bit channel words being associated with a coding state of said channel code C2, said coding state of said channel code C2 being established in dependence upon an end part of the preceding channel word in said sequence of channel words, and wherein end parts of the m1-bit channel words in a coding state of channel code C1 and beginning parts of the m2-bit channel words in a coding state of channel code C2 are arranged to comply with said runlength constraint.