A method and apparatus for estimating the value of a slider airbearing
resonance frequency involves obtaining a readback signal from a data
storage medium over a plurality of complete airbearing periods and
estimating the value of an airbearing resonance frequency using the
readback signal. In one embodiment, a discrete signal segment comprising a
plurality of frequency transform components is produced using the readback
signal information, and the value of the airbearing resonance frequency is
estimated using spectral leakage in the discrete signal segment. A ratio
of the magnitudes of a first DFT component to a second DFT component is
computed at each of a plurality of sampling rates. Each of these sampling
rates is defined by a number of samples per average airbearing cycle
multiplied by a frequency falling within a range of expected airbearing
frequencies associated with a given implementation. The second DFT
component is related to the slider airbearing resonance frequency, and the
first DFT component is a DFT component adjacent to or non-adjacent to the
second DFT component. The airbearing resonance frequency value is
estimated using a minimum of the ratios, which may also constitute DFT
component power ratios. A number of different frequency transform
techniques may be employed, including Discrete Fourier Transform, Fast
Fourier Transform, and Short-Time DFT techniques. One of several frequency
transform approaches may be implemented depending on whether the detected
airbearing signal is stationary or non-stationary. The airbearing
resonance frequency methodology may be implemented in-situ a data storage
system.
