Detection of hard-disc defect regions using soft decisions
AssigneeLSI Corporation
InventorsShaohua Yang, Weijun Tan
Life of this patent
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Abstract
In a hard-disc drive, a defect region on the hard disc is detected by generating two statistical measures (e.g., β1(k) and β2(k)) based on signal values (e.g., x[n] or y[n]) and soft-decision values (e.g., L[n]) corresponding to the signal values. The measures are compared to detect the location of the defect region of the hard drive. Using the soft-decision values reduces fluctuations in a ratio of the statistical measures compared to a ratio formed from statistical measures that are not based on soft-decision values, resulting in a more-reliable test for detecting defect regions.
Claims20
A machine-implemented method for detecting a defect region on a hard drive, the method comprising:
- (a) the machine generating a first measure based on signal values, x[n] y[n] expected signal values corresponding to the signal values, and soft-decision values L[n] corresponding to the signal values;
- (b) the machine generating a second measure based on expected signal values and defect-free soft-decision values corresponding to only defect-free regions of the hard drive;
- (c) the machine comparing the first and second measures;
- and
- (d) the machine detecting the defect region based on the comparison of step (c).
(canceled)
A machine for detecting a defect region on a hard drive, the machine comprising:
- (a) means for generating a first measure based on signal values, x[n] y[n] expected signal values corresponding to the signal values, and soft-decision values L [n] corresponding to the signal values;
- (b) means for generating a second measure based on expected signal values and defect-free soft-decision values corresponding to only defect-free regions of the hard drive;
- (c) means for comparing the first and second measures;
- and
- (d) means for detecting the defect region based on the comparison of means (c).
A non-transitory machine-readable storage medium, having encoded thereon program code, wherein, when the program code is executed by a machine, the machine implements a method for detecting a defect region on a hard drive, the method comprising:
- (a) generating a first measure based on signal values, x[n] y[n] expected signal values corresponding to the signal values, and soft-decision values L[n] corresponding to the signal values;
- (b) generating a second measure based on expected signal values and defect-free soft-decision values corresponding to only defect-free regions of the disk drive;
- (c) the machine comparing the first and second measures;
- and
- (d) the machine detecting the defect region based on the comparison of step (c).
Dependencies are inferred from the claim text.