A technique for the measurement of track misregistration in disk files

The authors describe a noninvasive technique for measuring track misregistration (TMR) in disk files using variations in read signal amplitude as an indicator of relative motion between the read head and the written track. The readback signal amplitude from a magnetic recording head can be used as a sensitive linear position transducer for measuring dynamic head-to-track misregistration in disk files. Subtracking the repeatable part of the signal amplitude eliminates virtually all non-TMR related modulation, leaving only small contributions from electronics noise and nonrepeatable fly height fluctuations. These error terms can be measured in isolation by locating the head directly on-track, where sensitivity to TMR vanishes. This technique can provide detailed information about the electromechanical performance of completely assembled and installed disk files. >