Method to minimize compatibility error in hierarchical modulation using variable phase
US7657225B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 26, 2006 |
| Grant date | Feb 2, 2010 |
| Priority date | — |
| Expiry date | Mar 6, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/3488
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The present invention provides a method of hierarchically modulating first and second digital data streams in a broadcast system such as an SDAR system that is compatible with legacy receivers. The second digital data stream, but not the first, is provided with a non-binary pseudo-random encoding. A carrier is first modulated, e.g. QPSK, by the first digital data stream; and a second modulation is performed with the encoded second digital data stream. The encoding includes a multiplication of a matrix formed of 2, 3 or 4 consecutive bits of the secondary data stream by a matrix, e.g. a Hadamard matrix to form a product matrix having non-binary values that are used to modify consecutive symbols of the first modulation. The second modulation appears as Gaussian noise to legacy receivers over time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.