Adaptive track shape control during self servo-write

1. A method of adaptive track shape control during a self servo-write process, said method comprising: detecting a first error in a targeted path for writing servo data onto a first track of a disk; correlating said first error with a second error for a targeted path in a previously written track of said disk which is separated from said first track by one read/write offset whereby said correlating said previously written track is based upon a read/write offset of a writing element and a reading element disposed within a read/write head; generating a correction for a feed-forward signal used to position a writing element which is used to write servo data for a subsequent track of said disk;

wherein said correlating further comprises:

determining a frequency harmonic of said first error based upon a rotation frequency of said disk; and determining a frequency harmonic of said second error based upon a rotation frequency of said disk; and

performing a discrete Fourier transform of a position error signal to determine said frequency harmonic of said first error; performing a discrete Fourier transform of a second position error signal to determine the frequency of said second error; accessing an offset between said writing element and a read element of a read/write head based upon a location of either of said first track and of said second track on said disk; and determining a measured sensitivity to each of a plurality of burst signals.

2. The method as recited in claim 1 further comprising:

determining a plurality of harmonic values based upon said rotation frequency of said disk; and

assigning a weighted value to at least one of said plurality of harmonic values when generating said correction.

3. The method as recited in claim 1 further comprising:

determining a coherence value describing the correlation between said error and said second error;

generating said correction when said coherence value exceeds a coherence threshold.

4. The method as recited in claim 1 further comprising:

determining a sample set comprising at least one servo writing operation;

using said corrected feed-forward signal to write said at least one subsequent track based upon a size of said sample set;

detecting a correlation between a third error in a shape of said at least one subsequent track and a previously written track which is separated from said at least one subsequent track by one read/write offset; and

correlating said third error with said error for said targeted path of said first track.

5. A method of adaptive track shape control during a self servo-write process, said method comprising:

determining a shape of a first track of a disk based upon a position error signal (PES) from servo data of said first track;

determining a shape of a second track of said disk which is separated from said first track by one read/write offset based upon a second PES from servo data of said second track;

detecting a correlation between an error in the shape of said first track and a second error in the shape of a second track;

generating a corrected feed-forward signal used to position a writing element used when writing servo data to said disk for at least one subsequent track;

accessing an offset between said writing element and a read element of a read/write head based upon the location of either of said first track and of said second track on said disk; and

determining a measured sensitivity to each of a plurality of burst signals.

6. The method as recited in claim 5 further comprising:

performing a discrete Fourier transform of said PES to determine the frequency of said error; and

performing a discrete Fourier transform of a second PES of said second track to determine the frequency of said second error.

7. The method as recited in claim 5 further comprising:

determining a plurality of harmonic values based upon a rotation frequency of said disk; and

assigning a weighted value to at least one of said plurality of harmonic values when generating said corrected feed-forward signal.

8. The method as recited in claim 5 further comprising:

determining a coherence value describing the correlation between said error and said second error;

generating said corrected feed-forward signal when said coherence value exceeds a coherence threshold.

9. The method as recited in claim 5 wherein said detecting said correlation further comprises:

selecting said second track based upon a read/write offset of said writing element and a reading element disposed within said read/write head.

10. The method as recited in claim 5 further comprising:

determining a sample set comprising at least one servo writing operation;

using said corrected feed-forward signal to write said at least one subsequent track based upon the size of said sample set;

detecting a correlation between a third error in the shape of said at least one subsequent track and a previously written track which is separated from said at least one subsequent track by one read/write offset; and

correlating said third error with said error for said targeted path of said first track.