Detecting a servo address mark (SAM) in a servo field sync-up operation
View Patent ↗A method for detecting a servo address mark (SAM) of a servo sector of a disk of a disk drive during a servo field sync-up operation is disclosed. The method includes: detecting a start of a preamble; opening a SAM search window to detect the SAM; and continuing to detect the presence of the preamble during a SAM search time period. Further, the method discloses that: if the preamble is detected, the SAM search window is continued; and if the preamble is not detected, and the SAM is not detected, the SAM search window is closed.
1. A method for detecting a servo address mark (SAM) of a servo sector of a disk during a servo field sync-up operation, the method comprising:
detecting a start of a preamble;
opening a SAM search window to detect the SAM; and
continuing to detect the presence of the preamble during a SAM search time period, wherein:
if the preamble is detected, continuing the SAM search window; and
if the preamble is not detected, and the SAM is not detected, closing the SAM search window.
2. The method of claim 1 , further comprising detecting the SAM.
3. The method of claim 2 , wherein the SAM search window is closed.
4. The method of claim 1 , wherein, if the SAM search time period times out, the SAM search window is closed.
5. The method of claim 1 , wherein the preamble detected is from a spiral wedge.
6. The method of claim 1 , wherein the preamble detected comprises a phase lock loop (PLL) field of the servo sector.
7. The method of claim 6 , wherein the servo sector further includes at least one of a track identification (TKID) field and a sector identifier field.
8. The method of claim 7 , wherein the servo sector further includes a group of servo bursts.
9. The method of claim 1 , wherein the SAM search window is closed after less than 50 nano-seconds.
10. The method of claim 1 , wherein the SAM search window to detect the SAM is opened in response to the detected preamble.
11. A disk drive comprising:
a head to read servo sectors;
a disk having a plurality of tracks, a substantial majority of the tracks having a plurality of servo sectors; and
a read/write channel coupled to the head to implement operations to detect a servo address mark (SAM) of a servo sector of the disk during a servo field sync-up operation, the operation comprising:
detecting a start of a preamble;
opening a SAM search window to detect the SAM;
continuing to detect the presence of the preamble during a SAM search time period, wherein:
if the preamble is detected, continuing the SAM search window; and
if the preamble is not detected, and the SAM is not detected, closing the SAM search window.
12. The disk drive of claim 11 , further comprising the read/write channel detecting the SAM.
13. The disk drive of claim 12 , further comprising the read/write channel closing the SAM search window.
14. The disk drive of claim 11 , wherein, if the SAM search time period times out, the read/write channel closes the SAM search window.
15. The disk drive of claim 11 , wherein the preamble detected is from a spiral wedge.
16. The disk drive of claim 11 , wherein the preamble detected comprises a phase lock loop (PLL) field of the servo sector.
17. The disk drive of claim 16 , wherein the read/write channel further includes at least one of a track identification (TKID) field and a sector identifier field.
18. The disk drive of claim 17 , wherein the servo sector further includes a group of servo bursts.
19. The disk drive of claim 11 , further comprising the read/write channel closing the SAM search window after less than 50 nano-seconds.
20. The disk drive of claim 11 , further comprising the read/write channel opening the SAM search window to detect the SAM in response to the detected preamble.
21. A disk drive comprising:
a disk having a plurality of tracks, a substantial majority of the tracks having a plurality of servo sectors;
means for detecting a start of a preamble of a servo sector of the disk;
means for opening a SAM search window to detect the SAM; and
means for continuing to detect the presence of the preamble during a SAM search time period, wherein:
if the preamble is detected, continuing the SAM search window; and
if the preamble is not detected, and the SAM is not detected, closing the SAM search window.
22. The disk drive of claim 21 , further comprising means for detecting the SAM.
23. The disk drive of claim 22 , further comprising means for closing the SAM search window.
24. The disk drive of claim 21 , wherein, if the SAM search time period times out, means for closing the SAM search window.
25. The disk drive of claim 21 , wherein the preamble detected is from a spiral wedge.
26. The disk drive of claim 21 , wherein the preamble detected comprises a phase lock loop (PLL) field of the servo sector.