Method and system for compensating for adjacent tracks during reading of data

• US 8,599,508 B1
• Filed: 02/14/2012
• Issued: 12/03/2013
• Est. Priority Date: 04/08/2010
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Burd, Gregory
• Primary Examiner(s): HINDI, NABIL Z
• Application Number:
  US13/372,759
• Time in Patent Office: 658 Days
• Field of Search: 369/47.1, 369/47.27, 369/44.37, 360/39, 360/46, 360/65, 360/77.14, 360/64, 360/73.08, 360/77.13, 360/73.04, 360/73.07
• US Class Current: 360/39
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/4886 relative to rotating disc
• CPC Class Codes: G11B 5/4976 Disposition of heads, e.g. matrix arrangement
• CPC Class Codes: G11B 5/584 for track following on tapes
• CPC Class Codes: G11B 5/596 for track following on disks G11B5/5526, G11B5/5552, G11B5/5565, G11B5/5582 take precedence

Abstract

A method for sampling a current track and an adjacent track of a storage medium includes using a first read head to read a first data stream from the current track, using a second read head to read a second data stream from the adjacent track, delaying one of the first and second data streams to account for a position difference between the first and second read heads, and controlling sampling of the first and second data streams to align the first and second data streams. Controlling the sampling may include applying a synchronous sampling signal to control the first and second read heads so that they sample at synchronous locations, or may include sampling the current and adjacent data tracks at asynchronous locations and interpolating the first and second data streams to provide aligned samples. A storage device may operate in accordance with the method.

Claims

1. A method for sampling a current track of a storage medium and an adjacent track of the storage medium, the method comprising:

using a first read head to read a first data stream from the current track;

using a second read head to read a second data stream from the adjacent track;

delaying one of the first data stream and the second data stream to account for a position difference between the first read head and the second read head; and

controlling sampling of the first data stream and the second data stream to align the first data stream and the second data stream.

2. The method of claim 1 wherein the controlling sampling comprises applying a synchronous sampling signal to control the first read head and the second read head so that they sample at synchronous locations in their respective data streams.

3. The method of claim 2 further comprising:

processing the first data stream and the second data stream to derive timing information and data from the first data stream; and

deriving the synchronous sampling signal from the timing information.

4. The method of claim 1 wherein the controlling sampling comprises:

sampling the current track with the first read head, and the adjacent track with the second read head, at asynchronous locations to provide the first and second data streams; and

interpolating the first data stream and the second data stream to provide aligned samples of the first and second data streams.

5. The method of claim 4 wherein:

the first and second data streams are synchronously clocked and have a bit rate; and

the sampling the current track with the first read head and the adjacent track with the second read head comprises sampling the current and adjacent data tracks at a sampling frequency higher than the bit rate.

6. The method of claim 1 wherein the controlling timing comprises:

applying a timing signal to control sampling by the first read head to provide the first data stream;

sampling the adjacent track with the second read head, at sampling locations asynchronous to the first read head, to provide the second data stream; and

interpolating the second data stream under control of the timing signal to provide samples of the second data stream aligned with samples of the first data stream.

7. The method of claim 6 further comprising:

processing the first data stream and the second data stream to derive timing information and data from the first data stream; and

deriving the timing signal from the timing information.

8. The method of claim 6 wherein:

the first and second data streams have a bit rate; and

the first and second read heads sample the current and adjacent tracks at a sampling frequency higher than the bit rate.

9. A storage device comprising:

a first read head that reads a first data stream from a current track of a storage medium;

a second read head that reads a second data stream from an adjacent track of the storage medium; and

a decoder that;

delays one of the first data stream and the second data stream to account for a position difference between the first read head and the second read head; and

controls sampling of the first data stream and the second data stream to align the first data stream and the second data stream.

10. The storage device of claim 9 wherein the decoder controls the sampling by applying a synchronous sampling signal to control the first read head and the second read head so that they sample at synchronous locations in their respective data streams.

11. The storage device of claim 10 wherein the decoder further:

processes the first data stream and the second data stream to derive timing information and data from the first data stream; and

derives the synchronous sampling signal from the timing information.

12. The storage device of claim 9 wherein the decoder controls the sampling by:

sampling the current track with the first read head, and the adjacent track with the second read head, at asynchronous locations to provide the first and second data streams; and

interpolating the first data stream and the second data stream to provide aligned samples of the first and second data streams.

13. The storage device of claim 12 wherein:

the first and second data streams are synchronously clocked and have a bit rate; and

the decoder samples the current track with the first read head and the adjacent track with the second read head by sampling each of the current and adjacent tracks at a sampling frequency higher than the bit rate.

14. The storage device of claim 9 wherein the decoder controls timing by:

applying a timing signal to control sampling by the first read head to provide the first data stream;

sampling the adjacent track with the second read head, at sampling locations asynchronous to the first read head, to provide the second data stream; and

interpolating the second data stream under control of the timing signal to provide samples of the second data stream aligned with samples of the first data stream.

15. The storage device of claim 14 wherein the decoder further:

processes the first data stream and the second data stream to derive timing information and data from the first data stream; and

derives the timing signal from the timing information.

16. The storage device of claim 14 wherein:

the first and second data streams have a bit rate; and

the first and second read heads sample the current and adjacent tracks at a sampling frequency higher than the bit rate.

17. A method of controlling read head position in a storage device having a plurality of read heads, the method comprising:

deriving a first parameter from a first read head that reads a first track of a plurality of tracks; and

deriving a second parameter from a second read head that reads a second track of the plurality of tracks;

wherein;

the first parameter represents a portion of a signal from the first read head attributable to overlap of the first read head over the second track; and

the second parameter represents a portion of a signal from the second read head attributable to overlap of the second read head over the first track;

the method further comprising;

controlling position of at least one of the read heads to achieve a desired relationship of the first and second parameters.

18. The method of claim 17 wherein:

the desired relationship is a predetermined relationship between the first and second parameters.

19. The method of claim 18 wherein the predetermined relationship is differing of the first and second parameters by a constant.

20. The method of claim 19 wherein the constant is zero.