Signal modulating method, signal modulating apparatus, signal demodulating method and signal demodulating apparatus

A coded signal stored on a record medium, said signal comprising an N-bit code string converted from an M-bit data string, where M and N are integers having a relation of M<N;

• said M-bit data being converted into the N-bit code in accordance with a conversion table;
• wherein the conversion table comprises a plurality of primary and secondary code word tables, each of said primary and secondary code word tables arranged in groups of tables, said groups of primary and secondary tables each respectively containing binary values which all have a pattern of at least some binary digits associated with the respective group;
• said primary code word tables containing code words in one-to-one correspondence with a plurality of available data words and arranged at least generally in a progression of DSV values from at least substantially a relative maximum DSV associated with a minimum data word toward a relative minimum DSV associated with a maximum data word;
• said secondary code word tables containing code words which correspond only with a portion of the available data words and wherein code words from said secondary tables have DSV values which are arranged at least generally in a progression of DSV values from at least substantially a relative minimum DSV toward relative maximum DSV and wherein the code words in the secondary tables correspond with a portion of the data words.