Method of dc-free 8/9 nrz coding using a unique sync word pattern
US4775985A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 6, 1987 |
| Grant date | Oct 4, 1988 |
| Priority date | — |
| Expiry date | Apr 6, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M5/145
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An 8/9 encoding scheme wherein the improvement comprises selectively outputting, in response to a sync control signal, a first and a second 9 bit code word that uniquely identify a synchronization point in the 9 bit data word stream. The first code word is 1 1111 1111.sub.2 (1FF.sub.16) if the digital sum variation (DVS) is less than zero and 0 0000 0000.sub.2 (000.sub.16) if the digital sum variation is greater than or equal to zero. The second code word is any .+-.1 CDS entry of the same CDS polarity as the first word. In a preferred embodiment of the invention, the second code word is 1 0101 0101.sub.2 or 155.sub.16 (CDS=+1) or 0 1010 1010.sub.2 or 0AA.sub.16 (CDS=-1).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.