Patent ID: 6937424

Claim:
In a data storage device, a method of reducing repeatable runout (RRO) error comprising: receiving a plurality of RRO measurements for a plurality of disk tracks; for each one of one or more RRO harmonics to be compensated: performing a discrete Fourier transform (DFT) on each RRO measurement for the RRO harmonic to identify a real value and an imaginary value associated with each disk track; identifying, from the real values, a first set of (n+1) polynomial coefficients of a first nth-order polynomial function as a function of disk track; identifying, from the imaginary values, a second set of (n+1) polynomial coefficients of a second nth-order polynomial function as a function of disk track; and storing the first and the second sets of (n+1) polynomial coefficients for use in RRO compensation.