Patent ID: 6084536
Filing Date: 2000-07-04
Classification: G11B,H03M,H04L

Abstract:
An apparatus for converting a sequence of m-bit information words into a modulated digital signal, where m is an integer, the apparatus comprisinginput means for receiving the sequence of m-bit information words, m-to-n bit converter means for converting the sequence of m-bit information words into a sequence of n-bit codewords, where n is an integer larger than m, the sequence of codewords forming the modulated signal, which signal comprises bit cells having a first signal value and bit cells having a second signal value,determining means for determining a coding state related to a digital sum value at the end of a modulated signal portion, which digital sum value denotes for said modulated signal portion a running value of a difference between the number of bit cells having the first signal value and the number of bit cells having the second signal value, the m-to-n bit converter means comprising selection means for selecting for the conversion a code word from a set of codewords that depends on the coding state, at least one of the digital sum values determining a first and a second coding state, the first and second coding state being determined in response to the information word that corresponds to the previous codeword,wherein the apparatus is adapted to form a modulated signal satisfying the requirement that the number of consecutive bit cells in the modulated signal having the same signal value does not exceed 7.