Patent ID: 7405898
Filing Date: 2008-07-29
Classification: G11B

Abstract:
1. A method for generating a Position Error Signal (PES) reference curve in a data storage device, the method comprising: scanning a distance of at least one Track Pitch (TP) in a cross-track direction in each servo-burst along a predefined path, wherein a TP is a vertical cross-track distance between adjacent Track Centre Lines (TCLs) in a storage field, each servo-burst is pre-written on a storage medium in the data storage device, each servo-burst comprises at least one servo-track, wherein each servo-track comprises a plurality of topographical features, wherein data is stored on the storage medium as the plurality of topographical features, the at least one TP in a servo-burst is scanned with a read head; calculating a plurality of differential signal samples, wherein a differential signal corresponds to a first read-back signal and a second read-back signal, a sample of the differential signal being equal to a difference between a corresponding first amplitude and a second amplitude and each sample including an in-phase sample and a corresponding quadrature sample having a 90-degree phase shift relative to the in-phase sample, wherein the first amplitude is computed for a first read-back signal corresponding to a first servo-burst, the second amplitude is computed for a second read-back signal corresponding to a second servo-burst, wherein a servo-track of the first servo-burst has an offset of TP/2 in the cross-track direction relative to a servo-track of the second servo-burst, an amplitude of a read-back signal is computed when a read head is moving parallel to at least one servo-track of a servo-burst; determining a plurality of normalized samples by normalizing each in-phase sample and corresponding quadrature sample to obtain a plurality of normalized in-phase samples and corresponding normalized quadrature samples by dividing each sample of each differential signal by a normalization constant, wherein the normalization constant is an average of a maximum magnitude of the first read-back signal and a maximum magnitude of the second read-back signal; and combining the plurality of normalized in-phase samples and corresponding normalized quadrature samples to generate the PES reference curve.