Systems and Methods for Phase Compensated Harmonic Sensing in Fly Height Control

A method for harmonics calculation, the method comprising:

• providing a harmonics calculation circuit;
• receiving a first data set representing a periodic data from a first region of a storage medium;
• calculating a first harmonic based on the first data set;
• receiving a second data set representing the periodic data from a second region of the storage medium;
• calculating a second harmonic based on the second data set;
• and
• phase aligning the second harmonic and the first harmonic to yield a phase aligned harmonic.

A storage device, the storage device comprising:

• a storage medium having a first region and a second region;
• a harmonic calculation circuit operable to receive a first data set corresponding to a periodic data pattern derived from the first region and a second data set corresponding to the periodic data pattern derived from the second region, and wherein the harmonic calculation circuit is operable to calculate a first harmonic based on a periodic data pattern and a second harmonic based on the periodic data pattern;
• a phase difference estimation circuit operable to calculate a phase difference between the first harmonic and the second harmonic;
• and
• a phase offset compensation circuit operable to align the second harmonic with the first harmonic to yield an aligned harmonic.