| 摘要 |
PROBLEM TO BE SOLVED: To make a portable terminal equipment small-sized and light weight and to reduce the power consumption by using an absolute value arithmetic operation for an arithmetic operation of branch metric in place of a square arithmetic operation in the Viterbi algorithm. SOLUTION: A maximum likelihood signal is estimated by using the Viterbi algorithm of a state number 2. 'Number of branches of the Viterbi algorithm of a state number 2 is 4. In the Viterbi algorithm, a branch metric value is a square of a difference (R-S) between an external input signal R101 and an estimate object signal S, but an absolute value of the difference (R-S) is used in place of the square of the difference (R-S). A 4-bit digital signal is used respectively for the external input signal RIOI and an output signal S of an estimate object signal generator 108. A subtractor 102 obtains the difference (R-S), that is, subtraction of the estimate object signal S from the input signal R. An absolute value computing element 103 obtains its absolute value|R-S|.
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