Patent ID: 8325432

Claim:
A circuit for determining harmonics, the circuit comprising: an analog to digital conversion circuit, wherein the analog to digital conversion circuit is operable to provide a first series of digital samples corresponding to a pattern within a first servo data region of a storage medium and a second series of digital samples corresponding to the pattern within a second servo data region of the storage medium; a harmonic calculation circuit operable to: calculate a first harmonic value for the first series of digital samples; calculate a second harmonic value for the first series of digital samples; calculate a first ratio of the first harmonic value to the second harmonic value; calculate a third harmonic value for the second series of digital samples; calculate a fourth harmonic value for the second series of digital samples; calculate a second ratio of the third harmonic value to the fourth harmonic value; and average at least the first ratio with the second ratio to yield an average ratio.