Patent ID: 7391583

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 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, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark, the method comprising: using the head internal to the disk drive to read the spiral tracks to generate a read signal; processing the read signal to detect a plurality of the sync marks in a spiral track crossing; selecting one out of the plurality of detected sync marks based on a reliability of the detected sync marks; generating a timing recovery measurement in response to the selected sync mark; synchronizing a servo write clock in response to the timing recovery measurement; processing the read signal representing the high frequency signal in the spiral track crossing to generate a position error signal (PES) used to maintain the head along a substantially circular target path; and using the servo write clock and the head internal to the disk drive to write the product servo sectors along the circular target path.