Method and implementation of in-situ absolute head medium spacing measurement

摘要

In a method based on readback signal for in-situ measuring of absolute head-medium spacing, a pre-encoded pattern in the magnetic medium on a disk has at least two harmonics with amplitudes such that a linear function of the logarithmic ratio of the spacing loss-term is formed in relation to testing frequencies. This linear function is applied to determine the absolute head-medium spacing directly through the multiplication of gradient of the linear function and the linear velocity between the head and the medium of the disk drive.