Quantum Corporation

Xiaodong Che

Pablo A Ziperovich

James Fitzpatrick

Kevin Dean Fisher

Jim Fitzpatrick

Determining a micro-jog parameter in a disk drive that employs a magneto-resistive (MR) transducer head assembly and a partial response (PRML) detector includes improved accuracy in measuring on-track signal strength by use of a matched filter technique. The matched filter includes circuitry for emulating a partial response signal expected to be produced by a selected test bit pattern prerecorded on the selected track. The matched filtering technique provides improved accuracy in measuring the detected signal strength as it provides an extremely narrow digital filter focused on the test bit pattern frequency. Improved determination of the micro-jog distance further includes measuring interference from adjacent tracks, the best error rate being achieved at micro-jog positions intermediate the maximum on-track signal strength and the minimum off-track interference. A novel digital detector for accurately measuring adjacent track interference also is disclosed.

Method using matched filters for determining head positioner micro-jog

A digital output magnetoresistive ('DOMR') head for magnetic playback comprising one or more 'pinned' magnetic layers having magnetic polar direction which does not rotate under an external field from the media, and a magnetic digital switching layer formed using either shape or crystalline anisotropy such that it has an easy axis parallel to the magnetic direction of the pinned layer or layers and two stable magnetization directions, parallel or antiparallel to the magnetization polar direction of the pinned layer or layers. Because of this dual stable state configuration the DOMR head produces a substantially digital output when reading magnetic information.

Digital output magnetoresistive (DOMR) head and methods associated

Write precomposition optimization for a partial response maximum likelihood ('PRME') magnetic recording chapel adapted to a mass production environment. Optimal write precompensation may be determined by writing a tribit data pattern known to produce worst case nonlinear transition shift ('NLTS') onto a magnetic recording medium; reading back the recorded data pattern; and calculating the mean-squared error ('MSE') for one or more of the equalized data sample levels associated with the PRML channel to be optimized. The writing and reading back process is repeated with varying amounts of precompensation applied to the written pattern. The optimal amount of write precompensation is determined eider by minimizing the MSE for a selected sample level or by minimizing MSE between the middle and the upper or lower of the ternary PRML sample levels.

Write precompensation optimization in a PRML channel using a selected

Synchronous detection of fine position servo burst information with a data transducer having an electrical width not less than about two-thirds a width of a data track within a partial response maximum likelihood (PRML) data channel is disclosed. The servo burst information is recorded on a storage medium as a pair or series of fractional-track-width sinewave concurrent burst patterns and includes an on-track phase generating a position error signal which varies linearly with head displacement about track centerline and at least one off-track phase generating a position error signal which varies linearly with head displacement about a position related to track boundary. The method includes steps of reading the on-track phase and the off-track phase with a head to provide an analog signal stream, amplifying and low pass filtering the signal stream to normalize gain of the signal stream, synchronously quantizing the signal stream to provide synchronous digital burst samples, multiplying the synchronous digital burst samples during servo sampling intervals by a normalization factor generated by a correlation signal generator to provide normalized samples, integrating normalized samples originating during the on-track phase to provide an on-track position error signal, and integrating normalized samples originating during the off-track phase to provide an off-track position error signal. Circuitry implementing the method including a discrete matched filter is also disclosed.

Synchronous detection of concurrent servo bursts for fine head position

Digitial output magnetoresistive (DOMR) head and methods associated

Write precompensation optimization for a partial response maximum likelihood ('PRML') magnetic recording channel adapted to a mass production environment. Optimal write precompensation may be determined by writing a tribit data pattern known to produce worst case nonlinear transition shift ('NLTS') onto a magnetic recording medium; reading back the recorded data pattern; and calculating the mean-squared error ('MSE') for one or more of the equalized data sample levels associated with the PRML channel to be optimized. The writing and reading back process is repeated with varying amounts of precompensation applied to the written pattern. The optimal amount of write precompensation is determined either by minimizing the MSE for a selected sample level or by minimizing MSE between the middle and the upper or lower of the ternary PRML sample levels.

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Sunnyvale, CA, United States of America

Xiaodong Che