Encoded TID with error detection and correction ability

• US 6,226,138 B1
• Filed: 09/29/1998
• Issued: 05/01/2001
• Est. Priority Date: 09/29/1998
• Status: Expired due to Fees

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Blaum, Mario, Kabelac, William John, Yu, Mantle Man-Hon
• Primary Examiner(s): KIM, WON TAE C
• Application Number:
  US09/162,927
• Time in Patent Office: 945 Days
• Field of Search: 360/48, 360/49, 369/59
• US Class Current: 360/48
• CPC Class Codes: G11B 20/1217 on discs
• CPC Class Codes: G11B 20/18 Error detection or correction; Testing , e.g. of drop-outs
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence
• CPC Class Codes: G11B 2020/1238 track, i.e. the entire a spirally or concentrically arranged path on which the recording marks are located
• CPC Class Codes: G11B 2020/1267 Address data
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 2220/2516 Hard disks
• CPC Class Codes: G11B 27/3027 used signal is digitally coded
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: H03M 13/47 Error detection, forward error correction or error protection, not provided for in groups H03M13/01 - H03M13/37

Abstract

A method of detecting and correcting reading errors of track identification (TID) of a magnetic data storage disk. The method comprises a means of constructing a encoded TID which is derived from generalized Gray code. The encoded TIDs have a distance of D between the adjacent code words, and a distance of at least 2D between non-adjacent code words within a band of M TIDS. The encoded TIDs can correct up to (D−1)/2 errors. The method also comprises means of encoding and decoding TIDS, and means of detecting and correcting errors with encoded TIDs.

Claims

1. A data storage medium having a plurality of encoded TIDs wherein:

a first distance between adjacent encoded TIDs is equal to D,

a second distance between non-adjacent encoded TIDs is greater than or equal to D, and

a third distance between any two non-adjacent encoded TIDs that lie within a band of M of said encoded TIDs is greater than or equal to 2D;

wherein D is greater than or equal to 3.

2. The medium of claim 1 wherein each of said TIDs comprises a pair of vectors (U(i), X(j)), wherein U(i) is an i^th element of a first generalized Gray code, and X(j) is a j^th element of a second generalized Gray code.

3. The medium of claim 2 wherein D=3 and M=127.

4. The medium of claim 2 wherein:

said first generalized Gray code is a set of 2^h of said code words U(i) having p bits and h information bits, where p is greater than h;

a second generalized Gray code is a set of 2^k code words X(j) having q bits and k information bits, where q is greater than k; and

wherein h is greater than or equal to k, and the sum of k and h is n;

and wherein each of said encoded TIDs comprises;

one of said code words U(i), and

one of said code words X(j)

wherein each encoded TID has n information bits, and

wherein said encoded TIDs are ordered as follows;

(U(1),X(0));

(U(1), X(1));

(U(2)X(1));

(U(2),X(2));

. . . ;

(U(2^k), X(2^k−

1));

(U(2^k),X(0));

(U(2^k+1), X(0));

(U(2^k+1));

. . . ;

(U(2^k+1), (X(2^k−

1));

(U(2^k+1), (X(0)), (U(2^h−

2^k+1), X(0));

(U(2^h−

2^k+1), X(1));

. . . ;

(U(2^h−

1));

X(2^k−

1));

(U(0), (X(2^k−

1));

(U(0), X(0));

(U(3), X(0));

(U(3), X(1));

(U(4), X(2));

. . . ;

U(2^k+2), X(2^k+2), X(2^k−

1));

U(2^k+2), X(0));

(U(2^k+3), X(0));

(U(2^k+3), X(1));

(U(2^k+4), X(1));

. . . ;

(U(2^k+1+2), X(2^k−

1);

(U(2^k+12);

(X(0));

(U(2^h−

2^k+3), X(0));

(U(2^h−

2^k+3), X(1));

(U(2^h−

2^k+4), X(2));

. . . ;

(U(2), X(2^k−

1));

(U(2), X(0));

(U(2^k−

1), X(0));

(U(2^k−

1), X(1));

(U(2^k), X(1));

. . . ;

(U(2^k+1−

1), X(2^k−

1));

(U(2^k+1−

1), X(0));

(U(2^k+1), X(0));

(U(2^k+1), X(1));

(U(2^k+1), X(1));

. . . ;

(U(2^k+2−

1), X(2^k−

1));

(U(2^k+2−

1), X(0));

(U(2^h−

1), X(0));

(U(2^h−

1), X(1));

(U(0), X(1));

U(0), X(2));

. . . ;

(U(2^k−

2), X(2^k−

1));

(U(2^k−

2), X(0)).

5. The medium of claim 2 wherein said distance D is equal to 3.

6. The medium of claim 1 wherein said data storage medium is a magnetic recording medium having a plurality of data storage tracks.

7. The medium of claim 1 further comprising a servo sector having the plurality of encoded TIDs.