# US 2013/0155539 A1 · Extended servo mark

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- Number: US 2013/0155539 A1
- Document ID: US20130155539A1
- Status: Published application
- Kind: A1
- Application number: 13/330,144
- Filed: 2011-12-19
- Published: 2013-06-20
- Earliest claimed: 2011-12-19
- Assignees: Seagate Technology LLC
- Inventors: Mustafa Can Ozturk; Puskal Prasad Pokharel; Barmeshwar Vikramaditya
- Web page: https://patentgrep.com/patent/US20130155539A1

## CPC

- G11B 20/1217: {on discs}
- G11B 5/59688: {Servo signal format patterns or signal processing thereof, e.g. dual, tri, quad, burst signal patterns}
- G11B 20/1816: {Testing}
- G11B 2020/1281: {Servo information}
- G11B 2220/2516: Hard disks
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

An extended servo mark word is used when an error is detected from a servo mark. For example, a servo mark associated with a disk drive track may be detected during a data access operation. In response to an error in detecting the servo mark, at least one adjacent bit is evaluated together with the servo address mark to overcome the error.

## Claims

### Claim 1

A method comprising using an extended servo mark word when an error is detected from a servo mark.

### Claim 2 (depends on 1)

The method of claim 1, wherein the extended servo mark word includes at least one adjacent bit to the servo mark.

### Claim 3 (depends on 1)

The method of claim 1, wherein the bit is directly adjacent to the servo mark.

### Claim 4 (depends on 3)

The method of claim 3, wherein the bit is part of a preamble.

### Claim 5 (depends on 3)

The method of claim 3, wherein the bit is part of a gray code.

### Claim 6 (depends on 1)

The method of claim 1, further comprising overcoming the error using the extended servo mark.

### Claim 7 (depends on 1)

The method of claim 1, wherein the error comprises a threshold number of erroneous bits occurring in any combination of the servo mark and at least one adjacent bit to the servo mark.

### Claim 8 (depends on 1)

The method of claim 1, further comprising:
reading a timestamp to verify the servo mark; and
discarding the servo mark if the timestamp falls outside a threshold value.

### Claim 9

A logic circuit configured to use an extended servo mark word when an error is detected from a servo mark.

### Claim 10 (depends on 9)

The logic circuit of claim 9 wherein the extended servo mark word includes at least one adjacent bit to the servo mark.

### Claim 11 (depends on 10)

The logic circuit of claim 10, wherein the bit is directly adjacent to the servo mark.

### Claim 12 (depends on 11)

The logic circuit of claim 11, wherein the bit is part of a preamble.

### Claim 13 (depends on 11)

The logic circuit of claim 11, wherein the bit is part of a gray code.

### Claim 14 (depends on 9)

The logic circuit of claim 9, further configured to overcome the error using the extended servo mark.

### Claim 15 (depends on 9)

The logic circuit of claim 9, wherein the error comprises a threshold number of erroneous bits occurring in any combination of the servo mark and at least one adjacent bit to the servo mark.

### Claim 16 (depends on 9)

The logic circuit of claim 9, further configured to:
read a timestamp to verify the servo mark; and
discard the servo mark if the timestamp falls outside a threshold value.

### Claim 17

A method comprising:
during a data access operation, detecting a servo mark associated with a disk drive track; and
in response to an error in detecting the servo mark, evaluating at least one adjacent bit together with the servo mark to overcome the error.

### Claim 18 (depends on 17)

The method of claim 17, wherein the adjacent bit comprises at least part of one of a gray code and a preamble.

### Claim 19 (depends on 17)

The method of claim 17, further comprising:
reading a timestamp to verify the detected servo mark; and
discarding the detected servo mark if the timestamp falls outside a threshold value.

### Claim 20 (depends on 17)

The method of claim 17, wherein overcoming the error comprises overcoming a threshold number of erroneous bits in any combination of the servo mark and the at least one adjacent bit.