Patent ID: 7391584

Claim:
A method of writing product servo sectors on 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, each spiral track comprises a high frequency signal interrupted periodically 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; detecting the sync marks from the read signal to generate a sync mark detect signal; generating a timing recovery measurement in response to the sync mark detect signal, wherein the timing recovery measurement comprises a sinusoidal component; generating a timing compensation value in response to the sync mark detect signal, wherein the timing compensation value estimates the sinusoidal component in the timing recovery measurement; generating a frequency control signal in response to the timing recovery measurement and the timing compensation value; generating a servo write clock in response to the frequency control signal; and using the servo write clock and the head internal to the disk drive to write the product servo sectors to the disk.