Method and apparatus for providing read and write skew offset

Abstract

The present invention is a method and apparatus for generating a skew or position offset signal for aligning the read element of an magneto-resistive (MR) head with the centerline of written data, during a read operation. The disk has a plurality of tracks each of which are divided into sectors. Two adjacent tracks are first erased and a calibration burst is written in the odd sectors, for example, the first and third sectors of one of the tracks. A calibration burst is also written in the even sectors, such as the second and fourth sectors of the adjacent track. Without adjusting the position of the MR head, the value of the calibration burst on the latter track is read. Since the read element is offset from the write element, it can read the values of the calibration bursts on the odd sectors of one track and the values of the calibration bursts on the even sectors of the other track. The average values of calibration bursts, E.sub.oddave and E.sub.evenave are obtained. An offset value corresponding to E.sub.oddave -E.sub.evenave =0 is obtained and an offset signal corresponding to this offset value is generated. A servo operation is then performed to align the center of the read element with the centerline of the written data. Alternatively, the value of the calibration burst E.sub.odd in the first odd sector, and the value of the calibration burst E.sub.even may be read to obtain an offset value corresponding to E.sub.odd -E.sub.even =0.