| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive receiver making it possible to execute viterbi decoding of soft decision, which easily obtain the large improvement of transmitting performance by furthermore multilevel without requiring the development of a new LSI even in the receiver of a multilevel modulation system of levels not smaller than four levels. SOLUTION: A soft decision judging reliability calculating circuit 17 is provided separately. Thus, when a received signal point is deviated from a demodulation signal point at the time of setting a signal point which is the nearest to the signal point of a received signal (received signal point) on a signal space to be the demodulation signal point and a signal point which is the second nearest to be a second adjacent signal point, reliability lower than that of the bit of another digit is calculated for the bit of a digit where values are different between the code of the demodulation signal point and the code of the second adjacent signal point and the calculated reliability is used. Thus, the receiver soft-decision-decoding a convolutional code is obtained by using a soft decision decoding circuit 29 corresponding to a BPSK modulation system which can be produced comparatively at low cost. |
