Patent ID: 8743671

Claim:
A method for adjusting a recording condition on an optical disc for writing information, by using codes whose minimum run length is 2T, and for reading out the information, by using an adaptive equalization procedure and a PRML procedure, the method for adjusting a recording condition comprising: a step of binarizing each of read-out signal waveforms acquired from the optical disc, by using the PRML procedure, so as to obtain each of first binarized bit arrays; a step of generating a second binarized bit array and a third binarized bit array, both of which have minimum run length of 2T or greater, by shifting an edge of interest in each of the first binarized bit arrays by 1T leftward and rightward, respectively; a step of generating a first target signal waveform corresponding to each of the first binarized bit arrays, a second target signal waveform corresponding to each of the second binarized bit arrays, and a third target signal waveform corresponding to each of the third binarized bit arrays; a step of calculating a first value equivalent to a difference between: a Euclidean distance from the second target signal waveform to the read-out signal waveform and a Euclidean distance from the first target signal waveform to the read-out signal waveform, and calculating a second value equivalent to a difference between: a Euclidean distance from the third target signal waveform to the read-out signal waveform and a Euclidean distance from the first target signal waveform to the read-out signal waveform; a step of calculating a shift evaluation value of the edge of interest, by using a differential value between the first value and the second value; and a step of calculating a jitter value corresponding to an error probability for the edge of interest, by using a sum of the first value and the second value; a step of using a pulse string including (N−1) pulses for forming a recorded mark having a length of NT, wherein N is an integer, and of adjusting a starting position of a last pulse in the pulse string, so as to minimize the edge shift evaluation value; wherein the adaptive equalization procedure sets each of tap coefficients C n to an average value of a pair of tap coefficients a n and a N-1-n located symmetrically with each other relative to the time axis, the tap coefficients a n being updated by using a LMS method.