Western Digital Technologies, Inc.

Agency for Science, Technology and Research

Wai Ee Wong

Guoxiao Guo

Donald Joseph Brunnett

Jianguo Zhou

Jie Yu

Jingliang Zhang

Jianyi Wang

Hui Li

Xiaotian Xu

Jinchuan Zheng

Abdullah Al Mamun

Weichun Ye

Kun Ma

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.

Disk drive correcting an error in a detected gray code

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo bursts. A number of burst correction values are generated by reading at least one of the servo bursts at a number of different radial locations across the disk. The burst correction values are filtered to generate filtered burst correction values, and the filtered burst correction values are downsampled to generate downsampled burst correction values. The downsampled burst correction values are written to the disk, and the head is servoed over the disk by reading the downsampled burst correction values from the disk.

Data storage device filtering burst correction values before downsampling the burst correction values

A disk drive is disclosed comprising a disk including a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises a servo preamble. A head is actuated over the disk, wherein the head is operable to generate a read signal. The disk drive further comprises control circuitry including an analog cutoff filter operable to filter the read signal to generate a filtered read signal. The filtered read signal is sampled to generate read samples. During a normal operating mode, the analog cutoff filter is configured to have a first bandwidth. During a measurement mode, the analog cutoff filter is configured to have a second bandwidth greater than the first bandwidth, and the read samples representing at least part of the servo preamble are processed to measure a signal-to-noise ratio (SNR) and/or a fly height of the head.

Disk drive increasing bandwidth of cutoff filter while reading servo sector preamble

A method for computing position error signal information of a transducer in a data storage system provides for different readback signals between adjacent tracks. The method involves a computation to obtain coarse position information from the servo bursts signals for track seeking and a computation to obtain a position indicator from the user data sector for more precise track following within the user data sector.

Detection of track misregistration within user data channel

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Singapore, Singapore

Wai Ee Wong