Selecting highest reliability sync mark in a sync mark window of a spiral servo track crossing
AssigneeWestern Digital Technologies, Inc.
InventorTehri S. Lee
Life of this patent
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Abstract
A method is disclosed for demodulating a spiral servo track recorded on a disk of a disk drive. The spiral servo track comprises a high frequency signal interrupted by a sync mark at a sync mark interval. A demodulation window is enabled relative to a spiral servo track crossing, and a plurality of sync marks are detected in a sync mark window of the demodulation window. A reliability metric is generated for each of the detected sync marks, wherein the reliability metrics are evaluated to select one of the detected sync marks. A clock is synchronized in response to the selected sync mark.
Claims16
A method of demodulating a spiral servo track recorded on a disk, the spiral servo track comprising a high frequency signal interrupted by a sync mark at a sync mark interval, the method comprising:
- enabling a demodulation window relative to a spiral servo track crossing;
- searching for a sync mark within a sync mark window of the demodulation window, wherein the sync mark window represents a time within the demodulation window that the sync mark is expected to occur;
- detecting a plurality of sync marks in the sync mark window;
- generating a reliability metric for each of the detected sync marks;
- evaluating the reliability metrics to select one of the detected sync marks;
- and
- synchronizing a clock in response to the selected sync mark.
A disk drive comprising:
- a disk comprising a spiral servo track, the spiral servo track comprising a high frequency signal interrupted by a sync mark at a sync mark interval;
- a head actuated over the disk;
- and
- control circuitry operable to:
- enable a demodulation window relative to a spiral servo track crossing;
- search for a sync mark within a sync mark window of the demodulation window, wherein the sync mark window represents a time within the demodulation window that the sync mark is expected to occur;
- detect a plurality of sync marks in the sync mark window;
- generate a reliability metric for each of the detected sync marks;
- evaluate the reliability metrics to select one of the detected sync marks;
- and
- synchronize a clock in response to the selected sync mark.
Dependencies are inferred from the claim text.