Procedure and device for phase ambiguity resolution in a trellis coded modulation system.

摘要

The device for phase ambiguity resolution uses the same branch metrics of the correlation type used by the Viterbi decoder. At each symbol time it chooses the best branch metric among those departing from the final state of the most probable path identified by the Viterbi decoder and accumulates it for a pre-set number of symbol times while observing whether the sum obtained exceeds or not a given threshold. In the former case the demodulated signal phase is considered to be correct while in the latter case the phase is considered to be erroneous and an algorithm for performing phase counter-rotation on the received signal is activated. <IMAGE>