Data storage device measuring difference between read signals when reading a preamble with multiple read elements

摘要

A data storage device is disclosed comprising a disk comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors, each data sector comprises a preamble, and the preambles of adjacent data tracks are recorded at different frequencies. A first read element and a second read element of a head are positioned over a first preamble of a first data track to generate a first read signal emanating from the first read element and a second read signal emanating from the second read element. A first metric is generated based on the first read signal and a second metric is generated based on the second read signal. A difference between the first metric and the second metric is generated and used, for example, to servo the head over the disk or to measure a radial offset between the read elements.