Patent ID: 7468855

Claim:
A disk drive comprising: (a) a disk comprising a plurality of spiral tracks, wherein: each spiral track comprises a high frequency signal interrupted periodically by a sync mark; the spiral tracks are spaced apart circumferentially by a substantially equal spacing; and the number of spiral tracks equals a non-integer multiple of product servo wedges; (b) an actuator arm; (c) a head coupled to a distal end of the actuator arm; (d) a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk; and (e) control circuitry operable to write product servo sectors on the disk to define the product servo wedges by: 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; generating a frequency control signal in response to the timing recovery measurement; 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.