PURPOSE: To attain the word synchronism by a viterbi decoder itself, by obtaining a carrier phase large in a metric increment for eliminating the uncertainty of the carrier phase.
CONSTITUTION: A metric increment operating circuit 20 discriminates a maximum metric value from a new metric value selected at a branch selecting circuit 203 when the synchronism is started, and a subtractor 22 calculates a difference with the maximum metric being 1 time slot before stored in a register 23 is calculated. Since this value becomes the increment of the maximum metric, the synchronism/asynchronism is discriminated with a threshold value circuit 40 by outputting this value to an integrator 30. The output phase of a phase shifter 10 is changed with this discriminating signal.
HIRATA YASUO
FURUYA YUKITSUNA
MURAKAMI SHIYUUJI
NAKAMURA KATSUHIRO
NIPPON ELECTRIC CO