1. A disk drive that compensates for servo track squeeze, the disk drive comprising:
a disk having tracks, the tracks including a servo sector having servo bursts spaced sequentially around a circumference of the track for use in track following;
a head to track-follow on the track, wherein track following includes the head reading the servo bursts; and
a processor to compensate for track squeeze by implementing operations including:
determining a track squeeze value for the servo sector based upon reading the servo bursts;
determining a position error signal (PES) value for the servo sector based upon the read servo bursts;
estimating a Squeeze Correction Coefficient (SCC) to account for PES sensing gain variation associated with the servo sector;
calculating a squeeze corrected PES value based upon the SCC and the PES value, wherein the squeeze corrected PES value is calculated by an equation: Squeeze Corrected PES Value=SCC(z)*PES value(z), wherein z=position and SCC(z)=(|N|+|Q|)(|N|nominal+|Q|nominal), where N and Q are burst measurements at position z; and
utilizing the squeeze corrected PES value in servo control.
2. The disk drive of claim 1, wherein the track squeeze value is calculated based upon a track squeeze model having calibrated parameters for a servo sector.
3. The disk drive of claim 1, wherein the SCC is based on the PES value and the track squeeze value.
4. The disk drive of claim 1, wherein N=|A\u2212B| and Q=|C\u2212D| from a 4-burst pattern.
5. The disk drive of claim 1, wherein the SCC for the servo sector is stored in the servo sector.
6. The disk drive of claim 5, wherein a written-in repeatable run-out (WRRO) track center correction value is stored in the servo sector.
7. The disk drive of claim 6, wherein an incremental WRRO correction value for one or more off-track positions is stored in the servo sector for use during track following at off-track positions from track center.
8. The disk drive of claim 6, wherein a positive incremental WRRO correction value and a negative incremental WRRO correction value are stored in the servo sector for use during track following at one or more off-track positions in a positive or negative direction from track center, respectively.
9. A method to compensate for servo track squeeze in a disk drive, the method comprising:
reading servo bursts of a servo sector of a disk during track following;
determining a track squeeze value for the servo sector based upon the read servo bursts;
determining a position error signal (PES) value for the servo sector based upon the read servo bursts;
estimating a Squeeze Correction Coefficient (SCC) to account for track squeeze induced PES sensing gain variation associated with the servo sector;
calculating a squeeze corrected PES value based upon the SCC and the PES value, wherein the squeeze corrected PES value is calculated by an equation: Squeeze Corrected PES Value=SCC(z)*PES value(z), wherein z=position and SCC(z)=(|N|+|Q|)(|N|nominal+|Q|nominal), where N and Q are burst measurements at position z; and
utilizing the squeeze corrected PES value in servo control to compensate for track squeeze.
10. The method of claim 9, further comprising calculating the track squeeze value based upon a track squeeze model having calibrated parameters for a servo sector.
11. The method of claim 9, further comprising estimating the SCC based upon the PES value and the track squeeze value.
12. The method of claim 11, further comprising storing the SCC for the servo sector in the servo sector.
13. The method of claim 12, further comprising storing a written-in repeatable run-out (WRRO) track center correction value in the servo sector.
14. The method of claim 13, further comprising storing an incremental WRRO correction value for one or more off-track positions in the servo sector for use during track following at off-track positions from track center.
15. The method of claim 13, further comprising storing a positive incremental WRRO correction value and a negative incremental WRRO correction value in the servo sector for use during track following at one or more off-track positions in a positive or negative direction from track center, respectively.
16. The method of claim 9, wherein N=|A\u2212B| and Q=|C\u2212D| from a 4-burst pattern.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A dietary supplement capsule consisting of between about 100 and about 1000 mg of phosphatidylserine complex, fish oil comprising between about 17 and about 130 mg of docosahexaenoic acid and between about 17 and about 130 mg of eicosapentaenoic acid, between about 4 and about 90 mg of Ginkgo Biloba, between 4 and 90 mg of Vitamin E, a blueberry extract, phosphatidylcholine, and one or more of gelatin, glycerin, water, beeswax, lecithin, cocoa, caramel, titanium dioxide, and a coloring agent.
2. The dietary supplement capsule of claim 1, wherein said Vitamin E provides about 10 IUs of Vitamin E.
3. The dietary supplement capsule of claim 1, wherein said phosphatidylserine complex in said dietary supplement capsule is present in an amount of about 500 mg, wherein said docosahexaenoic acid is present in an amount of about 60 mg, wherein said eicosapentaenoic acid is present in an amount of about 60 mg, and wherein said Vitamin E is present in an amount that provides about 10 IUs of Vitamin E.
4. The dietary supplement capsule of claim 3, wherein the phosphatidylserine complex includes about 25 to about 200 mg of pure phosphatidylserine.
5. The dietary supplement capsule of claim 3, wherein the phosphatidylserine complex includes about 100 mg of pure phosphatidylserine.
6. The dietary supplement capsule of claim 1, wherein said coloring agent is carmine.
7. A dietary supplement capsule consisting of about 100 mg of phosphatidylserine complex, fish oil comprising between about 60 mg of docosahexaenoic acid and about 60 mg of eicosapentaenoic acid, about 40 mg of Ginkgo Biloba, about 17 mg of blueberry powder, between 4 and 90 mg of d-alpha tocopherol, and about 14 mg of phosphatidylcholine, and one or more of gelatin, glycerin, water, beeswax, lecithin, cocoa, caramel, titanium dioxide, and a coloring agent.
8. The dietary supplement capsule of claim 7, wherein said dietary supplement capsule comprises about 6.7 mg of d-alpha tocopherol.
9. The dietary supplement capsule of claim 7, wherein said coloring agent is carmine.
10. A dietary supplement capsule consisting of about 100 mg of phosphatidylserine complex, fish oil comprising between about 60 mg of docosahexaenoic acid and about 60 mg of eicosapentaenoic acid, about 40 mg of Ginkgo Biloba, about 17 mg of blueberry powder, between 4 and 90 mg of Vitamin E, and about 14 mg of phosphatidylcholine, and one or more of gelatin, glycerin, water, beeswax, lecithin, cocoa, caramel, titanium dioxide, and a coloring agent.
11. The dietary supplement capsule of claim 10, wherein said Vitamin E provides about 10 IUs of Vitamin E.
12. The dietary supplement capsule of claim 10, wherein said coloring agent is carmine.