Disk drive margining read channel by biasing log-likelihood ratios of a nonbinary iterative decoder
AssigneeWestern Digital Technologies, Inc.
InventorPatrick J. Lee
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Abstract
A disk drive is disclosed comprising a head actuated over a disk and control circuitry operable to sample a read signal emanating from the head to generate read samples. First vectors of log-likelihood ratios (LLRs) are generated in response to the read samples, wherein each vector corresponds to a nonbinary symbol q in a set of symbols. The first vectors of LLRs are biased to generate biased vectors of LLRs, and the biased vectors of LLRs are decoded into a data sequence, wherein the biased vectors of LLRs increase an error rate of the data sequence.
Claims14
A disk drive comprising:
- a disk;
- a head actuated over the disk;
- and
- control circuitry operable to:
- sample a read signal emanating from the head to generate read samples;
- generate first vectors of log-likelihood ratios (LLRs) in response to the read samples, wherein each vector corresponds to a nonbinary symbol q in a set of symbols;
- bias the first vectors of LLRs to generate biased vectors of LLRs;
- and
- decode the biased vectors of LLRs into a data sequence, wherein the biased vectors of LLRs increase an error rate of the data sequence.
A method of operating a disk drive comprising a head actuated over a disk, the method comprising:
- sampling a read signal emanating from the head to generate read samples;
- generating first vectors of log-likelihood ratios (LLRs) in response to the read samples, wherein each vector corresponds to a nonbinary symbol q in a set of symbols;
- biasing the first vectors of LLRs to generate biased vectors of LLRs;
- and
- decoding the biased vectors of LLRs into a data sequence, wherein the biased vectors of LLRs increase an error rate of the data sequence.
Dependencies are inferred from the claim text.