Granted Patent B1

US 9,257,145 · App. 14/264,244 · Granted Feb 9, 2016

Abstract

Claims (49)

1. A disk drive comprising:

a disk comprising a track, wherein the track comprises a sync mark;

a head comprising a plurality of read sensors including a first read sensor, and a second read sensor separated from the first read sensor by a down-track spacing; and

control circuitry configured to:

generate a first time-stamp (TS 1 ) after detecting the sync mark using the first read sensor as the disk rotates;

generate a second time-stamp (TS 2 ) after detecting the sync mark using the second read sensor as the disk rotates; and

generate a calibration value representing the down-track spacing based on the TS 1 and the TS 2 .

2. The disk drive as recited in claim 1 , wherein the control circuitry is further configured to generate the calibration value based on a difference between the TS 1 and the TS 2 .

3. The disk drive as recited in claim 1 , wherein the control circuitry is further configured to:

sample a read signal generated by the first read sensor based on a reference clock to generate signal samples;

detect the sync mark based on the signal samples; and

generate the TS 1 based on the reference clock.

4. The disk drive as recited in claim 3 , wherein the control circuitry is further configured to:

detect a zero-phase start value based on the signal samples;

detect the sync mark based on the zero-phase start value;

clock a counter based on the reference clock;

generate an integer part of the TS 1 based on the counter when the sync mark is detected; and

generate a fractional part of the TS 1 based on the zero-phase start value.

5. The disk drive as recited in claim 1 , wherein the control circuitry is further configured to measure the down-track offset at a plurality of different radial locations across the disk.

6. The disk drive as recited in claim 1 , wherein the control circuitry is further configured to combine a first read signal generated by the first read sensor with a second read signal generated by the second read sensor based on the measured down-track spacing.

7. The disk drive as recited in claim 6 , wherein the control circuitry is further configured to combine samples of the first read signal with samples of the second read signal based on the measured down-track spacing.

8. The disk drive as recited in claim 1 , wherein the control circuitry is further configured to:

sample a first read signal generated by the first read sensor to generate first signal samples;

sample a second read signal generated by the second read sensor to generate second signal samples; and

execute a two-dimensional equalization of the first signal samples and the second signal samples.

9. The disk drive as recited in claim 8 , wherein the control circuitry is further configured to execute the two-dimensional equalization in order to reduce inter-track interference (ITI) in one dimension.

10. A method of operating a disk drive, the method comprising:

generating a first time-stamp (TS 1 ) after detecting a sync mark on a disk using a first read sensor as the disk rotates;

generating a second time-stamp (TS 2 ) after detecting the sync mark using a second read sensor as the disk rotates; and

generating a calibration value representing a down-track spacing between the first read sensor and the second read sensor based on the TS 1 and the TS 2 .

11. The method as recited in claim 10 , further comprising generating the calibration value based on a difference between the TS 1 and the TS 2 .

12. The method as recited in claim 10 , further comprising:

sampling a read signal generated by the first read sensor based on a reference clock to generate signal samples;

detecting the sync mark based on the signal samples; and

generating the TS 1 based on the reference clock.

13. The method as recited in claim 12 , further comprising:

detecting a zero-phase start value based on the signal samples;

detecting the sync mark based on the zero-phase start value;

clocking a counter based on the reference clock;

generating an integer part of the TS 1 based on the counter when the sync mark is detected; and

generating a fractional part of the TS 1 based on the zero-phase start value.

14. The method as recited in claim 10 , further comprising measuring the down-track offset at a plurality of different radial locations across the disk.

15. The method as recited in claim 10 , further comprising combining a first read signal generated by the first read sensor with a second read signal generated by the second read sensor based on the measured down-track spacing.

16. The method as recited in claim 15 , further comprising combining samples of the first read signal with samples of the second read signal based on the measured down-track spacing.

17. The method as recited in claim 10 , further comprising:

sampling a first read signal generated by the first read sensor to generate first signal samples;

sampling a second read signal generated by the second read sensor to generate second signal samples; and

executing a two-dimensional equalization of the first signal samples and the second signal samples.

18. The method as recited in claim 17 , further comprising executing the two-dimensional equalization in order to reduce inter-track interference (ITI) in one dimension.

Assignments (8)