Demodulation compensation for spiral servo tracks in hard disk drives

A hard disk drive comprising:

• hard disk means for storing data, the hard disk means having one or more spiral servo tracks written thereon, wherein each of the servo tracks comprises servo data comprising one or more synchronization symbols;
• head means for producing a waveform as the head moves across the servo track;
• sampler means for obtaining a plurality of samples of the waveform, wherein the plurality of samples of the waveform comprises one of the synchronization symbols;
• and
• processor means for
• determining an estimated location of a peak amplitude of the waveform with respect to the plurality of samples of the waveform,
• determining a sampling phase defined by a number of the samples between one of the synchronization symbols and a predetermined one of the samples of the waveform,
• determining a compensation amount based on a compensation curve and the sampling phase,
• determining a refined estimated location of the peak amplitude of the waveform based on the estimated location of the peak amplitude of the waveform and the compensation amount, and
• determining the location of the center of the servo track based on the refined estimated location of the peak amplitude of the waveform.

An apparatus for determining the location of the center of a servo track embodied in a recording medium, wherein the servo track comprises servo data comprising one or more synchronization symbols, the apparatus comprising:

• a sampler adapted to obtain a plurality of samples of a waveform produced as a head moves across the servo track, wherein the plurality of samples of the waveform comprises one of the synchronization symbols;
• and
• a processor adapted to
• determine an estimated location of a peak amplitude of the waveform with respect to the plurality of samples of the waveform,
• determine a sampling phase defined by a number of the samples between one of the synchronization symbols and a predetermined one of the samples of the waveform,
• determine a compensation amount based on a compensation curve and the sampling phase,
• determine a refined estimated location of the peak amplitude of the waveform based on the estimated location of the peak amplitude of the waveform and the compensation amount, and
• determine the location of the center of the servo track based on the refined estimated location of the peak amplitude of the waveform.

An apparatus for determining the location of the center of a servo track embodied in a recording medium, wherein the servo track comprises servo data comprising one or more synchronization symbols, the apparatus comprising:

• sampler means for obtaining a plurality of samples of a waveform produced as a head moves across the servo track, wherein the plurality of samples of the waveform comprises one of the synchronization symbols;
• and
• processor means for
• determining an estimated location of a peak amplitude of the waveform with respect to the plurality of samples of the waveform,
• determining a sampling phase defined by a number of the samples between one of the synchronization symbols and a predetermined one of the samples of the waveform,
• determining a compensation amount based on a compensation curve and the sampling phase,
• determining a refined estimated location of the peak amplitude of the waveform based on the estimated location of the peak amplitude of the waveform and the compensation amount, and
• determining the location of the center of the servo track based on the refined estimated location of the peak amplitude of the waveform.

A method for determining the location of the center of a servo track embodied in a recording medium, wherein the servo track comprises servo data comprising one or more synchronization symbols, and wherein a waveform is produced in a head as the head moves across the servo track, the method comprising:

• obtaining a plurality of samples of the waveform, wherein the plurality of samples of the waveform comprises one of the synchronization symbols;
• determining an estimated location of a peak amplitude of the waveform with respect to the plurality of samples of the waveform;
• determining a sampling phase defined by a number of the samples between one of the synchronization symbols and a predetermined one of the samples of the waveform;
• determining a compensation amount based on a compensation curve and the sampling phase;
• determining a refined estimated location of the peak amplitude of the waveform based on the estimated location of the peak amplitude of the waveform and the compensation amount;
• and
• determining the location of the center of the servo track based on the refined estimated location of the peak amplitude of the waveform.

A computer program embodied in a computer-readable recording medium embodying instructions executable by a computer for determining the location of the center of a servo track, wherein the servo track comprises servo data comprising one or more synchronization symbols, and wherein a waveform is produced in a head as the head moves across the servo track, the computer program comprising:

• determining an estimated location of a peak amplitude of the waveform with respect to a plurality of samples of the waveform, wherein the plurality of samples of the waveform comprises one of the synchronization symbols;
• determining a sampling phase defined by a number of the samples between one of the synchronization symbols and a predetermined one of the samples of the waveform;
• determining a compensation amount based on a compensation curve and the sampling phase;
• determining a refined estimated location of the peak amplitude of the waveform based on the estimated location of the peak amplitude of the waveform and the compensation amount;
• and
• determining the location of the center of the servo track based on the refined estimated location of the peak amplitude of the waveform.