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Abstract

A digital modulation system is disclosed in which a string of input data is divided at intervals of 8 bits and the resulting 8-bit data words are converted into 16-bit modulated digital code data words. Code conversion is made so that the resulting 16-bit modulation code words have two or more consective digits between the 2nd and the 15th bits, five or less consecutive digits between the 1st and the 16th bits, four or less consecutive digits between the 13th and the 16th bits, the absolute value of the CDS of all 16 bits in each modulation code block is not more than 4 and the absolute value of the DSV from the leading bit to an arbitrary bit in each modulation code block is not more than 5. Also, the number of consecutive digits in any portion of the digital data is not less than 2 and not more than 5 and the absolute value of the DSV is not more than 3 from the beginning of the coded data stream to any point therein. An error rate more favorable than the M.sup.2 code of conventional digital modulation systems may be achieved in order to realize short wave length recording on narrower tracks for high density recording in a digital video recorder.

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First Claim