Patent ID: 7301717

Claim:
A method of writing product servo sectors to a disk of a disk drive, the disk drive comprising control circuitry and a head disk assembly (HDA) comprising the disk, an actuator arm, a head coupled 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, wherein each spiral track comprises a high frequency signal interrupted by a sync mark at a sync mark interval, 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) integrating the read signal to generate a ramp signal representing a spiral track crossing; (c) generating a position error signal in response to the ramp signal, wherein the position error signal is generated relative to a difference between a target amplitude at the reference point of the ramp signal and an actual amplitude of the ramp signal when the target sync mark is detected; (d) using the position error signal to maintain the head internal to the disk drive along a servo track while writing product servo sectors along the servo track.