Patent ID: 6678108
Filing Date: 2004-01-13
Classification: G11B

Abstract:
Apparatus for identifying spindle imbalance in a hard disk drive comprising:a processor, said processor for receiving position error signal (PES) samples from a plurality of sectors of a predefined cylinder for a plurality of disk surfaces; said processor for measuring and storing said PES samples for a defined number of revolutions for each of said plurality of disk surfaces; said processor for computing a repeatable runout (RRO) of said PES samples for said defined number of revolutions; said processor for computing a first harmonic discrete Fourier transform (DFT) and a first harmonic phase of said RRO; said processor for computing a mean repeatable runout (MRRO); said processor for computing a first harmonic DFT and a first harmonic phase of said MRRO; said processor for each of said plurality of disk surfaces, for computing cross-correlation coefficients and summing said computed cross-correlation coefficients to identify a spindle imbalance factor; and said processor for comparing said identified spindle imbalance factor with a predefined threshold value to identify spindle imbalance in the hard disk drive.