Technique to obtain head-medium magnetic spacing in a disk drive

A technique is presented to determine the head-medium magnetic spacing utilizing square wave recording spectral measurements. Because spectral analysis does not give a unique separation of the spacing and the transition parameter, the transition parameter is first determined at low densities using time domain transition noise analysis. The total noise power versus density is utilized to determine the transition parameter variation with density due to record process nonlinearities. Spectral fitting gives both the spacing and the giant magnetoresistance gap length. It is shown this technique is robust by analysis of data on perpendicular media with both inductive and single pole heads.