Disk drive correcting an error in a detected gray code

Abstract

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by a plurality of servo sectors. An estimated track ID is generated and a plurality of proximate track IDs is generated having values proximate the estimated track ID. A set of Gray codes is generated each corresponding to the estimated track ID and the proximate track IDs, wherein each Gray code in the set of Gray codes comprises N bits, and M bits out of a high order of the N bits comprise the same value. A recorded Gray code is detected in a first servo sector to generate a detected Gray code, and an error in the detected Gray code is corrected by inverting at least one bit in the detected Gray code comprising a value that is different from the value of the corresponding bit in the M bits.

What is claimed is: 
     
         1 . A disk drive comprising:
 a disk comprising a plurality of tracks defined by a plurality of servo sectors;   a head actuated over the disk; and   control circuitry operable to:
 generate an estimated track ID representing an estimated radial location of the head; 
 detect a Gray code in a first servo sector to generate a detected Gray code; 
 convert a subset of the detected Gray code into a partial track ID; and 
 combine the estimated track ID with the partial track ID to generate a detected track ID. 
   
     
     
         2 . The disk drive as recited in  claim 1 , wherein the control circuitry is further operable to convert a plurality of the lower order bits of the detected Gray code into the partial track ID. 
     
     
         3 . A method of operating a disk drive, the disk drive comprising a head actuated over a disk comprising a plurality of tracks defined by a plurality of servo sectors, the method comprising:
 generating an estimated track ID representing an estimated radial location of the head;   detecting a Gray code in a first servo sector to generate a detected Gray code;   converting a subset of the detected Gray code into a partial track ID; and   combining the estimated track ID with the partial track ID to generate a detected track ID.   
     
     
         4 . The method as recited in  claim 3 , further comprising converting a plurality of the lower order bits of the detected Gray code into the partial track ID.