Method and apparatus of modulating/demodulating data for an optical recording medium

A method of demodulating a channel data written onto an optical recording medium, comprising the steps of:

• (a) reading a channel data from the optical recording medium, the channel data having been modulated from a source data using a table selected among a plurality of mapping tables based on at least one among the conditions of the value of a previous source data, the time when low-frequency suppression has been conducted, the value of subsequent modulated data, and whether or not RLL constraints are violated;
• and
• (b) demodulating the read channel data using a plurality of de-mapping tables in which a decoded data corresponding to the channel data is contained.

An apparatus of modulating a source data to be written onto an optical recording medium under the conditions of a given code rate and limited run length, comprising:

• a modulator modulating the source data based on a first mapping table and modulating the same source data based on a second mapping table, the first mapping table containing coded data corresponding to the source data, the second mapping table containing at least one coded data, capable of suppressing low frequency components, which at least one source data among all source data contained in the first mapping table is mapped to;
• and
• a controller selecting one of the modulated data based on at least one among the conditions of the value of the source data, the time when low-frequency suppression has been conducted, the value of subsequent modulated data, and whether or not RLL constraints are violated.

An apparatus of demodulating a channel data written onto an optical recording medium, comprising:

• a detector reading a channel data from the optical recording medium, the channel data having been modulated from a source data using a table selected among a plurality of mapping tables based on at least one among the conditions of the value of a previous source data, the time when low-frequency suppression has been conducted, the value of subsequent modulated data, and whether or not RLL constraints are violated;
• and
• a demodulator demodulating the read channel data using a plurality of de-mapping tables in which a decoded data corresponding to the channel data is contained.