Balanced delay and resolution for timing based servo systems

Patent metadata

Field	Value
Publication number	US-10141016-B2
Application number	US-201715439760-A
Country	US
Kind code	B2
Filing date	Feb 22, 2017
Priority date	Feb 22, 2017
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A tape drive-implemented method, according to one embodiment, includes: determining a number of lateral position estimates to use for calculating a lateral position value, receiving lateral position estimates from a single servo channel, calculating the lateral position value by using the number of lateral position estimates, and using the lateral position value to control a tape head actuator. Other systems, methods, and computer program products are described in additional embodiments.

First claim

What is claimed is:

1. A tape drive-implemented method, comprising:
determining a number of lateral position estimates to use for calculating a lateral position value;
receiving lateral position estimates from a single servo channel;
calculating the lateral position value by using the number of lateral position estimates; and
using the lateral position value to control a tape head actuator.

2. The tape drive-implemented method as presented in claim 1 , comprising:
determining a current speed of a magnetic tape,
wherein determining the number of lateral position estimates is based on the current speed of the magnetic tape.

3. The tape drive-implemented method as presented in claim 2 , wherein the number of lateral position estimates is also based on at least one parameter selected from a group of parameters consisting of: a vibration condition, media type, and an environmental condition.

4. The tape drive-implemented method as presented in claim 1 , wherein each of the lateral position estimates is determined from a respective sub-frame of a timing based servo track on a magnetic tape.

5. The tape drive-implemented method as presented in claim 4 , comprising:
storing at least some of the lateral position estimates in memory; and
retrieving the stored lateral position estimates from the memory to calculate the lateral position value.

6. The tape drive-implemented method as presented in claim 1 , comprising:
receiving lateral position estimates from a second servo channel;
calculating a second lateral position value by using a second number of lateral position estimates received from the second servo channel, the second number of lateral position estimates according to the number of lateral position estimates, wherein each of the lateral position estimates from the single servo channel is determined from a respective sub-frame of a timing based servo track on a magnetic tape, wherein each of the lateral position estimates from the second servo channel is determined from a respective sub-frame of a second timing based servo track on the magnetic tape; and
using the second lateral position value along with the lateral position value to control the tape head actuator.

7. The tape drive-implemented method as presented in claim 1 , comprising:
calculating an operating frequency of a track-following control loop using a current speed of a magnetic tape and number of lateral position estimates; and
applying the operating frequency to the track-following control loop.

8. The tape drive-implemented method as presented in claim 1 , comprising:
receiving additional estimates from the servo channel;
calculating a supplemental value using the received additional estimates; and
using the supplemental value to control a tape head actuator,
wherein the supplemental value is selected from a group consisting of: a current speed of a magnetic tape, and a magnetic tape skew value.

9. The tape drive-implemented method as presented in claim 1 , wherein calculating the lateral position value includes: calculating an arithmetic mean of the lateral position estimates, or calculating a weighted average of the lateral position estimates.

10. A computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to:
determine, by the processor, a number of lateral position estimates to use for calculating a lateral position value;
receive, by the processor, lateral position estimates from a single servo channel;
calculate, by the processor, the lateral position value using the number of lateral position estimates; and
use, by the processor, the lateral position value to control a tape head actuator.

11. The computer program product as presented in claim 10 , the program instructions executable by the processor to cause the processor to:
determine, by the processor, a current speed of a magnetic tape,
wherein determining the number of lateral position estimates is based on the current speed of the magnetic tape.

12. The computer program product as presented in claim 11 , wherein the number of lateral position estimates is also based on at least one parameter selected from a group of parameters consisting of: a vibration condition, media type, and an environmental condition.

13. The computer program product as presented in claim 10 , wherein each of the lateral position estimates is determined from a respective sub-frame of a timing based servo track on a magnetic tape.

14. The computer program product as presented in claim 13 , the program instructions executable by the processor to cause the processor to:
store, by the processor, at least some of the lateral position estimates in memory; and
retrieve, by the processor, the stored lateral position estimates from the memory to calculate the lateral position value.

15. The computer program product as presented in claim 10 , the program instructions executable by the processor to cause the processor to:
receive, by the processor, lateral position estimates from a second servo channel;
calculate, by the processor, a second lateral position value by using a second number of lateral position estimates received from the second servo channel, the second number of lateral position estimates according to the number of lateral position estimates, wherein each of the lateral position estimates from the single servo channel is determined from a respective sub-frame of a timing based servo track on a magnetic tape, wherein each of the lateral position estimates from the second servo channel is determined from a respective sub-frame of a second timing based servo track on the magnetic tape; and
use, by the processor, the second lateral position value along with the lateral position value to control the tape head actuator.

16. The computer program product as presented in claim 15 , the program instructions executable by the processor to cause the processor to:
receive, by the processor, lateral position estimates from a third servo channel;
calculate, by the processor, a third lateral position value by using a third number of lateral position estimates received from the third servo channel, the third number of lateral position estimates according to the number of lateral position estimates, wherein each of the lateral position estimates from the third servo channel is determined from a respective sub-frame of a third timing based servo track on the magnetic tape; and
use, by the processor, the third lateral position value along with the lateral position value and the second lateral position value to control the tape head actuator.

17. The computer program product as presented in claim 10 , the program instructions executable by the processor to cause the processor to:
calculate, by the processor, an operating frequency of a track-following control loop using a current speed of a magnetic tape and the number of lateral position estimates; and
apply, by the processor, the operating frequency to the track-following control loop.

18. The computer program product as presented in claim 10 , the program instructions executable by the processor to cause the processor to:
receive, by the processor, additional estimates from the servo channel;
calculate, by the processor, a supplemental value using the received additional estimates; and
use, by the processor, the supplemental value to control a tape head actuator,
wherein the supplemental value is selected from a group consisting of: a c

Assignees

• IBM

Inventors

• Bui Nhan X
• Cherubini Giovanni
• Furrer Simeon
• Inch Randy C
• Lantz Mark A
• Pantazi Angeliki

Classifications

• G11B5/5926 Primary

  recorded in separate tracks, e.g. servo tracks · CPC title

• G11B5/584 Primary

  for track following on tapes · CPC title