Patent ID: 7466246

Claim:
A modulation apparatus for converting data with a basic data length of m bits into variable length code (d k; m, n; r) with a basic code length of n bits where d is a minimum run and k is a run length limit, said modulation apparatus characterized by having conversion means for converting input data into code in accordance with a conversion table wherein said conversion table enforces a conversion rule, according to which the remainder of division of a ‘1’ count of an element in a data string by 2 having a value of 0 or 1 shall always be equal to the remainder of division of a ‘1’ count of an element in the string of code words resulting from conversion of said data string by 2 and conversion codes of said conversion table comprise: basic codes for d=1, k=7, m=2 and n=3; first substitution codes for limiting the number of consecutive appearances of said minimum run d; and second substitution codes for keeping said run length limit k.