Digital modulating method

A digital modulating method for coding M data bits into N channel bits (M<N) comprising the steps of selecting M and N to satisfy the relationship N=.alpha.M, and selecting .alpha. to be an integer equal to 2, and wherein said coding of said M data bits comprises eight to fourteen modulation and further comprising the step of selecting a pattern of successive fourteen channel bits in said N-channel bits and a pattern of the eight to fourteen modulation to be identical.

An information recording medium having recorded thereon digital signals modulated so that a minimum value of a number of successive "0"s sandwiched between "1" and "1" in a row of coded bits from M data bits into N channel bits (M<N) is a maximum, wherein the coded bits from M data bits are modulated according to eight to fourteen modulation and a pattern of fourteen channel bits in the N channel bits is identical to a pattern of the eight to fourteen modulation.

A digital demodulating circuit supplied with modulated data in which a word of a selected one of a plurality of second code signals of different relative bit numbers than said modulated data was installed at a junction adjacent successive words of a first code signal converted according to a predetermined conversion rule, comprising:

• separator means responsive to a signal identifying which one of the plurality of second code signals was inserted and for excluding said second code signal from said modulated data and extracting said first code signal;
• and
• converting means for converting said first code signal into original data according to said predetermined conversion rule.