International Business Machines Corporation

Thinh Huu Nguyen

Wayne Leung Cheung

Chorng-Kuang Wang

Chenhuei J Chaing

A digital servo system for a disk drive provides servo information signal demodulation. The system includes a digital demodulator including a burst signal accumulator that accumulates terms according to respective burst timing intervals to produce a digital, quadrature position error signal (PES). The demodulator also can include a dibit burst filter with synchronous dibit sampling preferably implemented as a Hilbert Transform filter. Alternatively, the demodulator does not include a filter and a squarer and, instead, the squarer comprises a sum-and-squarer that sums the squares of odd and even digitized samples. In another embodiment, the system employs a digital demodulator having a digital squarer that removes any phase component of the digitized servo information signal and includes a burst signal accumulator that accumulates the squared terms according to respective burst timing intervals to produce the PES. The demodulator may include a filter comprising a harmonic notch filter. A spilt burst servo pattern for the servo control system is comprised of half-width transitions that can be written in a signal pass of a recording head and therefore has no phase misalignment between adjacent flux patterns.

Digital pes demodulation for a disk drive servo control system using synchronous digital sampling

A disk head position control system having a disk head controller that moves a disk head relative to a surface of a magnetic media disk encoded with a plurality of tracks of a quadrature burst pattern includes a burst pattern that comprises an asynchronous, multi-frequency track address code having burst pattern transitions that extend across the width of a track and are arranged in staggered fashion in alternate tracks such that no transitions between adjacent tracks are aligned in the disk radial direction.

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Sunnyvale, CA, United States of America

Thinh Huu Nguyen