Patent ID: 7746749

Claim:
A look-ahead data detector for an optical disc system that performs a selection function from among a plurality of functions of a Viterbi detector, comprising: a processor: a boundary function generator in a signal communication with the processor for generating a plurality of decision logic variables A0L, A0R˜F0L, F0R, A7L, A7R˜F7F, and F7R at states 0 and 7 by applying a value of a current sample y0 that converts information stored in the optical disc system, values of consecutively input six future samples y1-y6, and estimating values of target samples px, pm, a, nm, and nx to a predetermined boundary function; a boundary decision unit in a signal communication with the processor for generating a plurality of boundary decision logic values R0, −R0, R7, and −R7 at the states 0 and 7 by using the plurality of decision logic variables A0L, A0R˜F0L, F0R, A7L, A7R˜F7F, and F7R; and a next state generator in a signal communication with the processor for deciding a next state by using the plurality of boundary decision logic values R0, −R0, R7, and −R7, wherein the boundary function generator, if the state 0 is at time t=k, separates all available output paths having consecutively input samples after time t=k+1 into two groups P and Q including the output paths via a next state 0 at the time t=k+1 and including the output paths via the next state 1 at the time t=k+1, calculates a Euclidian distance squared for corresponding permutation pairs included in the two groups, the boundary function being generated using a minimum distance event selected according to a selection value obtained from an inequality design equation of the Euclidian distance squared.