Study on the nonlinearity of the nonstationary impulse signal using reassigned time-frequency analysis

Conventional Fourier analysis gives adequate information about the dynamic characteristics of the slider air bearing for the stationary cases. ne intermittent contacts for the extremely narrow gap, however, generate nonlinear and nonstationary impulse signals. Time-frequency analysis is widely used to investigate the nonstationary signal. Several time-frequency analysis methods are compared for the slider vibration signal caused by the impact against an artificially induced scratch on the disk. The representative Wigner-Ville distribution may suffer from severe interferences by cross terms even though it gives good resolution both in time and frequency. The smoothing process improves the interference problem at the expense of resolution. In order to get better resolution and less interference, the reassignment method is employed. Among others the reassigned Gabor spectrogram shows the best resolution and readability with negligible interference.