Method and apparatus for adjusting data recorded on optical disc

A signal adjustment method comprising:

• receiving sample values a, b, c, d, and e, sequentially sampled from an input signal embodied as Run Length Limited (RLL) (2, 10) code;
• calculating a first average value of sample values a and b, a second average value of sample values b and c, a third average value of sample values c and d, and a fourth average value of sample values d and e so as to determine a period which is multiple times a basic pit period;
• if the signs of the calculated first average value, second average value, and third average values are +, −, + or −, +, − respectively, adjusting value a and value d so as to make the period which is multiple times a basic pit period to be equal to a minimum run length of the RLL code;
• outputting the adjusted signal;
• and
• reproducing data based on the outputted adjusted signal.

A signal adjustment method comprising:

• receiving sample values a, b, c, and d sequentially sampled from an input signal embodied as Run Length Limited (RLL) (1, 7) code;
• calculating a first average value of sample values a and b, a second average value of b and c, and a third average value of c and d so as to determine a period which is multiple times a basic pit period;
• if the signs of the calculated first average value, second average value, and third average value are +, −, + or −, +, −, respectively, comparing the absolute value of the first average value with the absolute value of the third average value, and if the absolute value of the first average value is smaller, adjusting value a, and if the absolute value of the third average value is smaller, adjusting value d, so as to make the period which is multiple times a basic pit period to be equal to a minimum run length of the RLL code;
• outputting the adjusted signal;
• and
• reproducing data based on the outputted adjusted signal.

A signal adjustment apparatus comprising:

• a waveform regulator which:
• detects a period of an input signal of a Run Length Limited (RLL) code by sequentially receiving data sampled from the input signal of the RLL code, averaging every two consecutive data samples, and determining the period which is multiple times the basic pit period based on how many consecutive averages have the same sign,
• determines whether the detected period which is multiple times the basic pit period is less than a minimum run length of the RLL code,
• adjusts the input signal if the detected period which is multiple times the basic pit period is smaller than the minimum run length of the RLL code, and
• outputs the adjusted input signal;
• and
• a Viterbi decoder which receives the output of the waveform regulator and performs decoding.