Patent ID: 8077427

Claim:
A method usable to control fly height of a head over a medium in a data storage device, the method comprising: (a) determining, in a read-back mode, a first value based on a first signal received by a read path of the data storage device, the first signal corresponding to pre-recorded data read from the medium and characterized by at least one periodic pattern, wherein the first value is generated by sampling the first signal at a first sampling frequency; (b) determining, in a loop-back mode, a second value based on a second signal received by the read path directly from a write path of the data storage device, the second signal bypassing the medium and characterized by the at least one periodic pattern, wherein the second value is generated by sampling the second signal at a second sampling frequency different from the first sampling frequency; (c) generating a third value based on the first and second values, wherein the third value is usable to control the fly height.