| 摘要 |
PROBLEM TO BE SOLVED: To improve error rate after waveform equalization, with a simple configuration, by using a third tap coefficient of a calculated negative value and outputting it as a tap coefficient for shaping the waveform of a composite signal, when the third tap coefficient that is not a negative value is not calcu lated. SOLUTION: A character signal decoding part 20 uses a first ideal waveform out of ideal waveforms stored in an ROM 23 and waveform equalization calculation processing is performed, each parameter for an attenuator value S22, an offset value S23, a timing value 23 and tap values TAP 0 to 7 is calculated, waveform equalization processing is performed, and a character signal S27 is decoded. At this time, when the value of the TAP 0 is negative, tap calculation is repeated again. When the recalculation of the tap coefficient is performed (n) times and the value of the TAP 0 is still negative, the TAP 0 of the negative value is used on the assumption that a pre-ghost is actually occuring. If the TAP 0 shows a value which is not negative after the recalculation of the tap coefficient, the recalculation is stopped and the TAP 0 is used.
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