说明：  The same two-stage decoder as above. However, when transforming the symbols prior to Viterbi decoding, the amplitude information is ignored and only the phase of the received symbol is employed in the metric computation stage.
(The same two-stage decoder as above. Howev er, when transforming the symbols prior to Viterbi decoding, the amplitude information is ignored and only t he phase of the received symbol is employed in th e metric computation stage.)