Patent ID: 7505223

Claim:
A method of writing spiral tracks for a disk drive, the method comprising: writing a first concentric reference track at a first radial location near an outer diameter of a disk surface; writing a second concentric reference track at a second radial location near an inner diameter of the disk surface; writing a third concentric reference track at a third radial location between the first and second radial locations; and prior to writing one of the spiral tracks: positioning a head over the first concentric reference track and reading the first concentric reference track; generating a first position error signal representing an offset of the head from the first radial location; positioning the head over the second concentric reference track and reading the second concentric reference track; generating a second position error signal representing an offset of the head from the second radial location; positioning the head over the third concentric reference track and reading the third concentric reference track; generating a third position error signal in response to the first position error signal, the second position error signal, and the third radial location; and adjusting a velocity profile for writing the spiral track in response to the first, second, and third position error signals.