Patent ID: 7616399

Claim:
A disk drive comprising: a moveable head; a disk having a plurality of tracks, a substantial majority of the tracks having a plurality of servo sectors including a plurality of servo bursts utilized in track following operations; and a servo controller to control track following operations with the moveable head, the servo controller to implement operations to preserve position error signal (PES) continuity during track following, the operations comprising: dividing tracks of the disk into a plurality of zones, wherein each zone includes zone boundaries; and utilizing a plurality of PES equations to generate a PES value for each zone based upon read servo bursts, the PES equations comprising: a first zone PES equation comprising K*(B+D−A−C)/(D−C); a second zone PES equation comprising K*(B+D−A−C)/(A−B); a third zone PES equation comprising K*(A+D−B−C)/(A−B); and a fourth zone PES equation comprising K*(A+D−B−C)/(C−D); wherein K is a constant determined by the zone boundaries; and A, B, C, and D are servo burst values.