Patent ID: 8649118

Claim:
A method for log likelihood ratio (LLR) manipulation of a hard disk drive detector output, comprising: collecting a set of LLR distribution data; determining at least one of a threshold or a threshold range for each symbol of the LLR distribution data based on the set of the LLR distribution data; monitoring an output of the hard disk drive detector, the output including a plurality of symbols corresponding to the output; applying a first rule to each symbol of the plurality of symbols corresponding to the output, the first rule including determining whether one of a plurality of signature events occurred, each signature event of the plurality of signature events including a hard decision for a true value based upon LLR distribution patterns; when one of the plurality of signature events is determined to occur, setting a first LLR value of a symbol of the set of LLR distribution data to zero and applying a first penalty value to any other LLR value of the symbol that equals zero; applying a second rule to each symbol of the plurality of symbols corresponding to the output, the second rule including determining whether one of the plurality of signature events involves all but one LLR value of the symbol in the hard decision occurred; and when one of the plurality of signature events which involves all but one LLR value of the symbol in the hard decision is determined to occur, applying a second penalty value to all LLR values but the one LLR value.