| 摘要 |
A method for detecting aberrations in a digital data storage medium, such as a magnetic media disk. In a media certifier, a series of signal pulses is produced by reading data previously written to a medium is examined for differential variations between each signal pulse and at least one other of those signal pulses in the local area of the medium. A signal indicative of such differential variations is isolated by means of a CYCOMP circuit (54) and/or a band reject circuit (140). The CYCOMP circuit (54) works by delaying a previously produced signal for comparison to the cycle of the signal presently being produced and then producing a differential signal representing any instantaneous difference between the two signals. The band reject circuit (140) works by eliminating any frequency content that would be present in a series of normal signals and thus isolating any asynchronous signal that is indicative of an aberration. Both the CYCOMP circuit (54) and the band reject circuit (140) use comparators (114), (118) and (152) to determine if any detected differential signal rises above a preset error indication threshold.
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