Data storage device initializing read signal gain to detect servo seed pattern
View Patent ↗A data storage device is disclosed comprising a disk comprising at least one servo seed pattern, and a head actuated over the disk. An amplitude measurement is generated based on a read signal emanating from the head while reading the disk. A number of times the amplitude measurement exceeds a first threshold is first counted during a first revolution of the disk, and a number of times the amplitude measurement exceeds the first threshold is second counted during a second revolution of the disk. The servo seed pattern is detected based on the first count and the second count.
1. A data storage device comprising:
a disk comprising at least one servo seed pattern;
a head actuated over the disk; and
control circuitry configured to:
generate an amplitude measurement based on a read signal emanating from the head while reading the disk;
first count a number of times the amplitude measurement exceeds a first threshold during a first revolution of the disk;
second count a number of times the amplitude measurement exceeds the first threshold during a second revolution of the disk; and
detect the servo seed pattern based on the first count and the second count.
2. The data storage device as recited in claim 1 , wherein when a first delta between the first count and the second count is greater than a second threshold, the control circuitry is further configured to:
adjust a gain of the read signal; and
detect the servo seed pattern based on the adjusted gain of the read signal.
3. The data storage device as recited in claim 2 , wherein prior to detecting the servo seed pattern the control circuitry is further configured to:
third count a number of times the amplitude measurement exceeds the first threshold during a third revolution of the disk;
fourth count a number of times the amplitude measurement exceeds the first threshold during a fourth revolution of the disk; and
validate the adjusted gain of the read signal when a second delta between the third count and the fourth count is less than the second threshold.
4. The data storage device as recited in claim 3 , wherein the control circuitry is further configured to continue adjusting the gain of the read signal until the delta is less than the second threshold.
5. The data storage device as recited in claim 1 , wherein when a first delta between the first count and the second count is greater than a second threshold, the control circuitry is further configured to:
adjust the first threshold; and
detect the servo seed pattern based on the adjusted first threshold.
6. The data storage device as recited in claim 5 , wherein prior to detecting the servo seed pattern the control circuitry is further configured to:
third count a number of times the amplitude measurement exceeds the first threshold during a third revolution of the disk;
fourth count a number of times the amplitude measurement exceeds the first threshold during a fourth revolution of the disk; and
validate the adjusted first threshold when a second delta between the third count and the fourth count is less than the second threshold.
7. The data storage device as recited in claim 6 , wherein the control circuitry is further configured to continue adjusting the first threshold until the delta is less than the second threshold.
8. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to detect the servo seed pattern by opening a servo seed pattern window based on when the amplitude measurement exceeds the first threshold relative to a rotation angle of the disk.
9. The data storage device as recited in claim 8 , wherein the control circuitry is further configured to open the servo seed pattern window based on when the amplitude measurement exceeds the first threshold during the first disk revolution and when the amplitude measurement exceeds the first threshold during the second disk revolution at the same rotation angle of the disk.
10. A method of operating a data storage device, the method comprising:
generating an amplitude measurement based on a read signal emanating from a head while reading a disk;
first counting a number of times the amplitude measurement exceeds a first threshold during a first revolution of the disk;
second counting a number of times the amplitude measurement exceeds the first threshold during a second revolution of the disk; and
detecting a servo seed pattern on the disk based on the first count and the second count.
11. The method as recited in claim 10 , wherein when a first delta between the first count and the second count is greater than a second threshold, the method further comprises:
adjusting a gain of the read signal; and
detecting the servo seed pattern based on the adjusted gain of the read signal.
12. The method as recited in claim 11 , wherein prior to detecting the servo seed pattern the method further comprises:
third counting a number of times the amplitude measurement exceeds the first threshold during a third revolution of the disk;
fourth counting a number of times the amplitude measurement exceeds the first threshold during a fourth revolution of the disk; and
validating the adjusted gain of the read signal when a second delta between the third count and the fourth count is less than the second threshold.
13. The method as recited in claim 12 , further comprising to continue adjusting the gain of the read signal until the delta is less than the second threshold.
14. The method as recited in claim 10 , wherein when a first delta between the first count and the second count is greater than a second threshold, the method further comprises:
adjusting the first threshold; and
detecting the servo seed pattern based on the adjusted first threshold.
15. The method as recited in claim 14 , wherein prior to detecting the servo seed pattern the method further comprises:
third counting a number of times the amplitude measurement exceeds the first threshold during a third revolution of the disk;
fourth counting a number of times the amplitude measurement exceeds the first threshold during a fourth revolution of the disk; and
validating the adjusted first threshold when a second delta between the third count and the fourth count is less than the second threshold.
16. The method as recited in claim 15 , further comprising to continue adjusting the first threshold until the delta is less than the second threshold.
17. The method as recited in claim 10 , further comprising detecting the servo seed pattern by opening a servo seed pattern window based on when the amplitude measurement exceeds the first threshold relative to a rotation angle of the disk.
18. The method as recited in claim 17 , further comprising opening the servo seed pattern window based on when the amplitude measurement exceeds the first threshold during the first disk revolution and when the amplitude measurement exceeds the first threshold during the second disk revolution at the same rotation angle of the disk.