Compensation for nonlinearity in servo patterns

Patent metadata

Field	Value
Publication number	US-10650852-B2
Application number	US-201916290758-A
Country	US
Kind code	B2
Filing date	Mar 1, 2019
Priority date	Jul 24, 2018
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

A method according to one embodiment includes generating a y-position estimate based on a servo readback signal, and determining a nonlinearity-correction value corresponding to the y-position estimate. The method further includes adjusting the y-position estimate using the nonlinearity-correction value. A computer program product for compensating for nonlinearity in a timing based servo pattern according to another embodiment includes a computer readable storage medium having program instructions embodied therewith. The program instructions are readable and/or executable by a controller to cause the controller to perform the foregoing method. An apparatus according to another embodiment includes a controller configured to perform the foregoing method.

First claim

What is claimed is:

1. A method, comprising:
generating a y-position estimate based on a servo readback signal;
determining a nonlinearity-correction value corresponding to the y-position estimate by interpolation using nonlinearity-correction values corresponding to known locations in a vicinity of the estimated y-position; and
adjusting the y-position estimate using the nonlinearity-correction value.

2. The method as recited in claim 1 , wherein determining the nonlinearity-correction value corresponding to the y-position estimate includes retrieving the nonlinearity-correction value from a table.

3. The method as recited in claim 1 , wherein determining the nonlinearity-correction value corresponding to the y-position estimate includes retrieving the nonlinearity-correction value from a source selected from the group consisting of: a magnetic tape cartridge memory, data stored on a magnetic tape, and a magnetic tape library memory.

4. The method as recited in claim 1 , wherein the nonlinearity-correction value is determined by using a function for directly computing the nonlinearity-correction value as a function of the y-position estimate.

5. The method as recited in claim 1 , comprising:
generating a second y-position estimate based on a second servo readback signal;
determining a second nonlinearity-correction value corresponding to the second y-position estimate; and
adjusting the second y-position estimate using the second nonlinearity-correction value.

6. A computer program product for compensating for nonlinearity in a timing based servo pattern, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable and/or executable by a controller to cause the controller to:
generate, by the controller, a y-position estimate based on a servo readback signal;
determine, by the controller, a nonlinearity-correction value corresponding to the y-position estimate by using a function for directly computing the nonlinearity-correction value as a function of the y-position estimate; and
adjust, by the controller, the y-position estimate using the nonlinearity-correction value.

7. The computer program product as recited in claim 6 , wherein determining the nonlinearity-correction value corresponding to the y-position estimate includes retrieving the nonlinearity-correction value from a table.

8. The computer program product as recited in claim 6 , wherein the nonlinearity-correction value is determined by interpolation using nonlinearity-correction values corresponding to known locations in a vicinity of the estimated y-position.

9. The computer program product as recited in claim 6 , the program instructions readable and/or executable by the controller to cause the controller to:
generate, by the controller, a second y-position estimate based on a second servo readback signal;
determine, by the controller, a second nonlinearity-correction value corresponding to the second y-position estimate; and
adjust, by the controller, the second y-position estimate using the second nonlinearity-correction value.

10. An apparatus, comprising:
a controller configured to:
generate a y-position estimate based on a servo readback signal;
determine a nonlinearity-correction value corresponding to the y-position estimate,
wherein determining the nonlinearity-correction value corresponding to the y-position estimate includes retrieving the nonlinearity-correction value from a table,
wherein the table includes a plurality of nonlinearity-correction values corresponding to known locations relative to a servo band,
wherein the servo readback signal includes a signal from a servo reader reading the servo band; and
adjust the y-position estimate using the nonlinearity-correction value.

11. The apparatus as recited in claim 10 , wherein determining the nonlinearity-correction value corresponding to the y-position estimate includes retrieving the nonlinearity-correction value from a source selected from the group consisting of: a magnetic tape cartridge memory, data stored on a magnetic tape, and a magnetic tape library memory.

12. The apparatus as recited in claim 10 , wherein the nonlinearity-correction value corresponding to the y-position estimate is determined by interpolation using nonlinearity-correction values corresponding to known locations in a vicinity of the estimated y-position.

13. The apparatus as recited in claim 10 , wherein the nonlinearity-correction value is determined by using a function for directly computing the nonlinearity-correction value as a function of the y-position estimate.

14. The apparatus as recited in claim 10 , wherein the controller is further configured to:
generate a second y-position estimate based on a second servo readback signal;
determine a second nonlinearity-correction value corresponding to the second y-position estimate; and
adjust the second y-position estimate using the second nonlinearity-correction value.

15. The apparatus as recited in claim 14 , wherein the nonlinearity-correction value is determined by using a function for directly computing the nonlinearity-correction value as a function of the y-position estimate, wherein the second nonlinearity-correction value is determined by using a second function for directly computing the nonlinearity-correction value as a function of the second y-position estimate, wherein the function and second functions are different.

16. The apparatus as recited in claim 10 , the controller is configured to: use the adjusted y-position estimate for adjusting a head position of a magnetic tape head thereafter reading a servo band, wherein the servo readback signal includes a signal from a servo reader of the magnetic tape head reading the servo band.

Assignees

• IBM

Inventors

• Judd Kevin B
• Furrer Simeon
• Pantazi Angeliki
• Lantz Mark A

Classifications

• G11B5/00873

  the segments being disposed in different longitudinal zones of the tape · CPC title

• G11B5/5543

  servo-format therefor · CPC title

• G11B5/584

  for track following on tapes · CPC title

• G11B5/56 Primary

  with provision for moving the head {support} for the purpose of adjusting the position of the head relative to the record carrier, e.g. manual adjustment for azimuth correction or track centering ({G11B5/52,} G11B5/54, G11B5/58 take precedence) · CPC title