a conversion section configured to convert the equalized waveform into a maximum likelihood sequence by carrying out metric calculation based on average values of the equalized waveform in {HEAD ~ vicinities} of a positive signal level, a negative signal level and {TAIL ~ a zero signal level} 
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a conversion section configured to convert the equalized waveform into a maximum likelihood sequence by carrying out metric calculation based on average values of the equalized waveform in { HEAD ~ vicinities } of a positive signal level , a negative signal level and { TAIL ~ a zero signal level }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL