|United States Patent Application||20060276145|
|Walker; Glenn A. ; et al.||December 7, 2006|
Method to minimize compatibility error in hierarchical modulation using variable phase
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.
|Inventors:||Walker; Glenn A.; (Greentown, IN) ; DiBiaso; Eric A.; (Kokomo, IN) ; Hiatt; Michael L. JR.; (Westfield, IN)|
|Correspondence Name and Address:|| |
DELPHI TECHNOLOGIES, INC.
|Filed:||June 26, 2006|
|U.S. Current Class:||455/102|
|U.S. Class at Publication:||455/102|
|Intern'l Class:||H04B 1/02 20060101 H04B001/02; H04B 1/66 20060101 H04B001/66|
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