A practical end-to-end all-digital multiresolution system is demonstrated that employs joint source-channel coding and modulation in order to achieve efficient broadcast of digital HDTV. The threshold effect plaguing single resolution systems is softened by a stepwise graceful degradation. This can be used to increase the coverage and robustness of the digital broadcast system. This approach is seen as an alternative to traditional single resolution digital transmission systems which are not designed for broadcast situations, and which suffer from the threshold effect. This paper highlight the benefits of using ans embedded multiresolution modulation constellation over a modulation scheme that resort to time or frequency multiplexing of the broadcast resolution. Besides showing coding results and simulation of transmission effects, the paper discusses the trade-offs between low and high resolution coverage
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