Patent Number: 8,792,202

Title: Disk drive adjusting rotation speed of disk to compensate for blind area when measuring frequency response of servo control system

Abstract: A disk drive is disclosed comprising a head and a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors. The disk drive further comprises control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The disk is rotated at a first speed and the servo sectors are read at a first servo sample frequency to generate first servo samples. The disk is rotated at a second speed different from the first speed and the servo sectors are read at a second servo sample frequency to generate second servo samples. The second servo samples are processed to measure a frequency response of the servo control system proximate the first servo sample frequency.

Inventors: Wan; Jie (Singapore, SG), Xu; Xiaotian (Singapore, SG), Cao; Shuyu (Singapore, SG), Tan; Jern Khang (Muar, MY), Guo; Guoxiao (Irvine, CA), Xi; Wei (Mission Viejo, CA)

Assignee: Western Digital Technologies, Inc.

International Classification: G11B 5/596 (20060101); G11B 20/20 (20060101)

Expiration Date: 7/29/12018