| 摘要 |
Systems and methods for removing phase shifts due to hierarchical modulat ion to improve synchronization and performance in legacy and hierarchical de coders are disclosed. Methods of compensating for the effects of hierarchica l modulation can, for example, comprise receiving an I, Q symbol that has be en further modulated by an overlay phase shift, detecting the direction of t he overlay phase shift, de-rotating the symbol by a defined angle correspond ing to the overlay phase shift and the direction, and passing the symbol to legacy synchronization and forward error correction decoding stages after th e de-rotating. A receiver implementing the methods is disclosed. The methods provide a simple solution to compensating for overlay modulation without re quiring modification of any proven algorithms within legacy demodulator desi gns. The methods allow for essentially any offset angle used in an overlay m odulation scheme to have minimal effect on signal acquisition and performanc e.
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