Method and device for adding or extracting a secondary information signal to/from a RLL code sequence
US7038600B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 14, 2001 |
| Grant date | May 2, 2006 |
| Priority date | — |
| Expiry date | Nov 4, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2020/1469
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and device for adding or extracting a secondary information signal to/from a runlength-limited code sequence, includes detecting a polarity of a runlength at a first predetermined position of the runlength-limited code sequence and setting a parameter reflecting the degree of freedom that is present in the runlength-limited channel code, e.g., the selection of a merging bit pattern in the CD-standard, on the basis of the detected polarity so as to obtain a predetermined polarity of a runlength at a subsequent second predetermined position of the runlength-limited code sequence. The predetermined polarity then corresponds to a binary value of the secondary information. Thus, a side-channel with a small capacity is provided, which is positioned very close to the physical channel such that the secondary information is hard to be detected from the EFM bit stream. Therefore, the side-channel can be used as a hidden channel for copy protection purposes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.