Patent ID: 6989774
Filing Date: 2006-01-24
Classification: G11B,H03M

Abstract:
1. An encoder comprising: information sequence generating means for generating a first information sequence by inserting a first DC control bit into an input information sequence at predetermined intervals and for generating a second information sequence by inserting a second DC control bit different from the first DC control bit into the input information sequence at the predetermined intervals; first code converting means for generating a first provisional code sequence by making a code conversion of the first information sequence generated by the information sequence generating means at a conversion ratio of an information word length m to an code word length n; second code converting means for generating a second provisional code sequence by making a code conversion of the second information sequence generated by the information sequence generating means at the conversion ratio of the information word length m to the code word length n; first delay means for delaying the first provisional code sequence generated by the first code converting means; second delay means for delaying the second provisional code sequence generated by the second code converting means; and selecting means for selecting either the first provisional code sequence generated by the first code converting means and delayed by the first delay means or the second provisional code sequence generated by the second code converting means and delayed by the second delay means, wherein the first and second code converting means use a coding rule by which, in case the coding rule is represented by a finite-state code conversion table, code words are assigned to information words so that a two's complement of a sum of coding bits included in the first provisional code sequence is always different from a two's complement of a sum of coding bits included in the second provisional code sequence when a first code state of the first provisional code sequence encoded starting with a predetermined original state, is identical to a second code state of the second provisional code sequence encoded starting with the predetermined original state.