| 摘要 |
A digital modulator is disclosed for handling primary and auxiliary frames of binary information as part of a two channel communication system. The modulator includes a primary frame-to-vector mapper for generating primary symbol vectors in accordance with quadrature amplitude and phase shift keying (QAM), and an auxiliary frame-to-vector mapper for generating auxiliary vectors in the In-Phase and Quadrature (I-Q) signal space. For those auxiliary vectors having endpoints lying within a given first area, the endpoints are mapped into a second area that represents an optimum auxiliary signal content given a primary symbol constellation in the I-Q plane. A mapped auxiliary vector is then added to an associated primary symbol vector. A carrier is then modulated in accordance with the sum vector.
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