| 摘要 |
PROBLEM TO BE SOLVED: To avoid reduction in a coding gain caused by suppression of a signal component at a required frequency band in a band limit filter. SOLUTION: A characteristics detection circuit 23 detects in advance how much a signal level of which frequency band is suppressed and stores the result to a storage device 25 by a band pass filter(BPF) 8. Then an orthogonal detection circuit 12 converts an output of the band pass filter 8 into I and Q data, a phase conversion circuit 32 converts the I and Q data, an equalizer 24 amplifies a signal level of the frequency band on the basis of correction information stored in the storage section 25 by a designated level, a P/S conversion circuit 26 converts the amplified signal into serial data, and a soft decision Viterbi decoder 30 applies soft decision to the data to decode the data. In this case, since the soft decision Viterbi decoder 30 receives the signal after the correction by the equalizer 24, the reduction in the coding gain caused by the suppression of the signal level by the band pass filter 8 can be avoided.
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