Patent ID: 8189286

Claim:
A disk drive comprising: a disk comprising a plurality of servo sectors that define a plurality of servo tracks, wherein the servo sectors comprise a plurality of servo bursts including: a first servo burst; a second servo burst following the first servo burst and offset radially in a first direction by approximately one half of a servo track from the first servo burst; a third servo burst following the second servo burst and offset radially in the first direction by approximately one full servo track from the second servo burst; and a fourth servo burst following the third servo burst and offset radially in a second direction opposite the first direction by approximately one half of a servo track from the third servo burst; a head actuated over the disk; and control circuitry operable to: position the head over a servo track; read at least two of the servo bursts; generate a numerator in response to: (i) the first and fourth servo bursts, (ii) the second and third servo bursts, or (iii) the first, second, third, and fourth servo bursts; generate a denominator in response to a difference between two of the servo bursts; generate a position error signal (PES) in response to a ratio of the numerator and the denominator; and position the head over the disk in response to the PES.