Patent ID: 7499236

Claim:
A method associated with a disk drive, the disk drive comprising control circuitry and a head disk assembly (HDA) comprising a disk, an actuator arm, a head connected to a distal end of the actuator arm, and a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk, the disk comprising a plurality of spiral tracks, each spiral track comprising a high frequency signal interrupted at a predetermined interval by a sync mark, the method comprising the steps of: (a) using the head internal to the disk drive to read the spiral tracks to generate a read signal; (b) using burst demodulation circuitry to demodulate the read signal representing the high frequency signal between the sync marks in one of the spiral tracks into a plurality of respective servo burst signals; (c) processing the servo burst signals generated from reading the spiral track to generate a position error signal (PES) used to maintain the head along a substantially circular target path; and (d) calibrating a correlation between the position error signal and an off-track displacement of the head.