| 摘要 |
An apparatus and method for detecting defects in the magnetic medium of a disk drive system includes sampling the output signal of the read channel of the system to provide a sampled output signal. In one embodiment, the sampled output signals from the read channel is squared. A delayed sampled output signal is also provided. The squared sampled output signal is summed with the delayed squared output signal. The square of the expected value of the sum of the squared sampled output signal and the delayed squared output signal is subtracted from the sum to provide a difference output signal. A threshold detector determines when the difference output signal of the subtraction means exceeds a predetermined threshold to provide an output signal indicative of a defect in the medium. One threshold detector determines when the absolute value of the difference output signal exceeds a predetermined threshold value. Another threshold detector determines when the difference output signal of the subtraction means exceeds either a predetermined upper threshold value or a predetermined lower value. The expected value may be a constant. In another embodiment, the absolute value of the sampled output signal and a delayed sampled absolute-value output signal are summed together.
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