METHOD FOR MODULATING CODE WITH DC COMPONENT ELIMINATED, AND DEMODULATION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a method for modulating and demodulating codes, including a method for eliminating the DC component of a code string to be modulated at recording data in an optical information storage medium. SOLUTION: This method comprises a step for deciding a control time point for periodically suppressing DC to a code string of which the source data are converted, a step for performing code conversion so that a running digital summation(RDS) of a code string is branched into a pair of code strings in the ascending and descending directions at each of the DC suppression control points, and a step for the most frequently bounded route around '0' of RDSs among the routes of code strings branched at each of the control time points. Therefore, the more quantity of DC can be eliminated with efficiency by regularly performing the code suppression control at code conversion and selecting the more bounded route of a code string at the DC suppression control time point.