Patent ID: 7502197

Claim:
A disk drive comprising: (a) a disk comprising a first set of time-based servo patterns and a second set of time-based servo patterns that define a plurality of servo tracks, wherein: the first set of time-based servo patterns comprises a first cyclical pattern that repeats radially over the disk; the second set of time-based servo patterns comprises a second cyclical pattern that repeats radially over the disk; each cyclical pattern comprises a plurality of timing marks; and one of the first cyclical patterns overlaps at least part of a first servo track, and one of the second cyclical patterns overlaps at least part of the first servo track; (b) a head actuated over the disk; and (c) control circuitry operable to demodulate at least one of the first and second set of time-based servo patterns to generate a control signal used to position the head over the disk by: detecting a first time interval relative to the timing marks; detecting a second time interval relative to the timing marks; and generating the control signal in response to the first and second time intervals; wherein the first cyclical pattern overlaps the entire first servo track, and the second cyclical pattern overlaps a portion of the first servo track.