Digital modulation apparatus, a digital modulation method, and a recording medium therefor
US5917857A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Dec 11, 1996 |
| Grant date | Jun 29, 1999 |
| Priority date | — |
| Expiry date | Dec 11, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/1426
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A digital modulation apparatus applies a method for converting data words to runlength-limited code words using plural conversion tables. The data words are converted to code words that significantly suppress the low frequency component of the final nonreturn-to-zero inverted signal. This digital modulation apparatus includes ROM tables for storing plural conversion tables containing the runlength-limited code words corresponding to the data words; end-runlength memories and evaluators for determining whether the runlength-limit constraints are satisfied in the interconnection between two consecutive code words when the data words to be converted are supplied; and a DSV controller for storing each of the code words that can be selected from two conversion tables to buffer memories when the runlength-limit constraints are satisfied, and selecting the code words wit the greatest effect suppressing the low frequency component in the obtained signal when the code words are NRZI converted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.