METHOD AND DEVICE FOR MODULATION/DEMODULATION WITH SUBSEQUENT LIMITATION OF THE MINIMUM LENGTH OF A SERIES OF IDENTICAL SIGNS IN AN ENCODING WORD

摘要

The method and the device can be used for data recording with high recording density and for the reproduction of data recorded on a memory medium with high recording density. They reduce any errors during the recording and the data reproduction and restrict the growing of errors in demodulation. The invention includes a unit for the determination/introduction of the bit for DSV (Digital Sum Value) control (11) which the DSV control performs in a series of input data and transmits it to the modulation unit (12). The latter converts the series of data with basic data length of 2 bits in a code of changing length with basic code length of 3 bits in accordance with the conversion table and passes the code produced by the conversion to a unit NRZI (Non Return to Zero Inverted) (13). The conversion table used by the modulation unit (12) contains substitution codes for limiting the number of the consecutive appearance of a minimum series to a predetermined value and substitution codes for preserving the boundary of the length of the series. In addition the conversion table applies a strict rule in accordance with which the residue of division into 2 of the number of digits in an element to a series of data having values of 0 or 1 should always be equal to the remainder of division into 2 of the number of digits in an element into a code produced by the conversion of the sequence of data. 31 claims, 11 figures