DISK DRIVE USING MULTIPLE SERVO TIMING MARKS THAT FORM A CODE OF UNIQUE INTERRELATED BIT PATTERNS

摘要

AbstractA disk drive (102) has a plurality of servo sectors (120) containing error-detectableand error-correctable servo timing marks (STMs) (121, 221, 213). Each STM is apattern of n bits, with each track having m unique STM patterns, each pattern having aminimum distance d to every other pattern, where d is greater than one. The error-tolerant STMs use a code of fixed bit patterns, with minimum Hamming distance againstall the patterns in the search, called d. These patterns may include bits associated withservo sectors, such as track index, servo sector number, and recording head number.The drive includes STM decoding circuitry (400) that recognizes valid STMs when d iswithin predetermined limits. The drive allows a tradeoff between error correction anderror detection. The STM decoding circuitry (400) is adaptive by allowing the errorcorrection and error detection comparison values to be updatable.