| 摘要 |
In a digital modulation method, digital data is supplied to a conversion table, and the digital data is converted into serial data. The serial data is supplied to a first fixed contact of a selector and is switched to data for a sync pattern from a sync pattern table, the sync pattern being supplied to a second fixed contact. From the selector, 93-data serial data including the 2-data sync pattern at the head thereof is extracted. The serial data is supplied to an exclusive-OR circuit, and the exclusive-OR output is fed back through a delay circuit, thereby generating NRZI data to be recorded. A digital sum value (DSV) of the NRZI data varies in accordance with the selection of conversion tables. The DSV is arbitrarily controlled, and sub-information is inserted by performing the control in a predetermined format.
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