Patent ID: 7075746

Claim:
A disk drive, comprising: an actuator assembly having a read/write head; a spindle motor; a disk mounted for rotation on the spindle motor and including a recording surface having a plurality of tracks, each track including a plurality of servo wedges; a wedge to wedge timer configured to measure a time elapsed between at least two successive detections of circumferentially adjacent servo wedges and to output a wedge to wedge correction signal that is dependent upon the measured elapsed time; a servo frequency generator configured to output a servo frequency generator signal having a frequency that is modulated by the wedge to wedge correction signal; a spindle motor control timer configured to output a spindle control timer signal that defines a count between circumferentially adjacent servo wedges that is dependent upon the servo frequency generator signal and upon the time elapsed between at least two successive detections of circumferentially adjacent servo wedges, and a spindle motor controller for controlling the spindle motor with a control signal that changes according to the count of the spindle control timer signal.