Patent ID: 7158338

Claim:
A servo control system for positioning a magnetic head adjacent a surface of a magnetic storage medium for reading a servo pattern longitudinally recorded on the magnetic storage medium, the system comprising: a head assembly having at least one read head for reading a servo track recorded on the storage medium and generating a read signal representative of the servo track; an actuator configured to adjust the relative position of the head assembly to the storage medium; and a servo controller configured to control the actuator based on the read signal, wherein the servo controller identifies servo frames within the servo track, each servo frame having a tone field of repeating servo marks providing a metric reference for dimensional measurements and a mid-frame synchronization mark within the tone field of repeating servo marks, wherein the mid-frame synchronization mark is distinguishable from the tone field, and the number of servo marks in the tone field of the servo frame along a longitudinal direction of the servo track before the mid-frame synchronization mark and after the mid-frame synchronization mark varies with lateral position, and determine a relative position of the read head to the servo track based on a number of servo marks before the mid-frame synchronization mark and after the mid-frame synchronization mark.