| 摘要 |
PCT No. PCT/JP94/00890 Sec. 371 Date Jan. 30, 1995 Sec. 102(e) Date Jan. 30, 1995 PCT Filed Jun. 2, 1994 PCT Pub. No. WO94/29990 PCT Pub. Date Dec. 22, 1994The phase of a received signal is detected by a phase detector at symbol intervals T relative to the phase of a local signal. The detected phase is input to delay circuits that are connected in series and each of which has the delay interval T. Phases PSI n (where n=0, 1, . . . , N) with delays of 1 to N symbols are output to a metric calculating portion. The sum of a partial sequence { DELTA phi i; i=n+1-q, n+2-q, . . . , n} of a N-symbol phase difference sequence candidate { DELTA phi n; n=0, 1, . . . , N} is added to a detected phase PSI n-q at a time point (n-q)T (where q=1, 2, . . . , N) so as to obtain an estimated value of the received signal phase PSI n. The v-th power value of the absolute value of a difference mu n(q) between the estimated value and the received signal phase is defined as a branch metric of q-symbol differential phase detection. SIGMA | mu n(q)|v= lambda n, which the summation of metrics from q=1 to n, is defined as a branch metric at the time point nT. A path metric LAMBDA = SIGMA lambda n, which is the summation of branch metrics from a time point 1T to a time point NT, is calculated for all N-symbol phase difference candidates. A candidate sequence with a minimum value is decided as a decoded sequence.
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