Patent ID: 7016131
Filing Date: 2006-03-21
Classification: G11B

Abstract:
1. A method for measuring absolute head-medium spacing between a head and a magnetic medium in a disk drive, the method comprising: encoding a code pattern on the magnetic medium; obtaining a spacing loss-term from the code pattern; applying a logarithmic ratio of the spacing loss-term to compute the absolute head-medium spacing; detecting a readback signal of the code pattern through the head, where the readback signal provides at least two harmonic signals with amplitudes; isolating the at least two harmonic signals to obtain a logarithmic ratio of the harmonic amplitudes; and obtaining the logarithmic ratio of the spacing loss-term from the logarithmic ratio of the harmonic amplitudes, which forms a linear relationship with a testing frequency, wherein the detecting of the readback signals, the isolating of the harmonic signals, and the obtaining of the logarithmic ratio of the spacing loss-term is repeated to obtain a plurality of logarithmic ratios of the spacing loss-term occurring at a plurality of test frequencies.