Digital carrier combining apparatus in a multiple QAM digital television signal receiver
AssigneeThomson Consumer Electronics, Inc.
InventorsTian J. Wang, Lauren A. Christopher
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Abstract
In a high definition television signal encoder, high priority and standard priority digital data are each separated into quadrature I and Q components, spectrally shaped by digital filtering, and time division multiplexed to produce respective quadrature amplitude modulated signals of the 32-QAM type. The high priority QAM signal and the standard priority QAM signal exhibit different bandwidths and carrier frequencies. The high priority and standard priority QAM signals are combined in digital form to produce a prioritized dual 32-QAM digital signal before being conveyed to a single analog-to-digital converter and analog RF transmission networks.
Claims9
In a system for processing a high definition television signal, apparatus comprising:
- means for providing a first digital signal representing first information and having quadrature components;
- means for providing a second digital signal representing second information and having quadrature components;
- first digital signal processing means responsive to said first and second digital signals for providing a first carrier quadrature amplitude modulated (QAM) with said first information and having a first data rate, and a second carrier quadrature amplitude modulated with said second information and having a second data rate different from said first data rate;
- and
- second digital signal processing means including means for converting said first data rate of said first modulated carrier to said second data rate of said second modulated carrier to produce a data rate converted modulated first carrier, and means for combining said data rate converted modulated first carrier and said modulated second carrier, in digital form, to produce a composite multiple QAM carrier output signal.
Dependencies are inferred from the claim text.