《Autocorrelation-Approaches-Time-Frequency-Analysis-Machinery-Vibration》.pdf

AUTOCORRELATION APPROACHES TO TIME FREQUENCY ANALYSIS OF MACHINERY VIBRATION SIGNALS Howard A. Gaberson, Chairman Diagnostics Prognostics Committee Machinery Failure Prevention Technology Society 234 Corsicana Drive Oxnard, CA 93030 ABSTRACT preserving sharp resolution, but they compromise amplitude accuracy. You may read that most of the time frequency This paper discusses the technical aspects of three well- distributions have been shown to be members of Cohens known time frequency analyses of machinery vibration class of distributions [3]. Each can be obtained from his signals. It begins by reviewing the short time Fourier general form with different kernels or selection functions. My transforms. It then considers the Wiener Kinchine theorem, work has shown that the Choi and Williams distribution which relates the autocorrelation function to the square of (CWD) [2] yields impressive detail and a significant structure the Fourier transform magnitudes. The symmetrical in the time frequency plane. Impact is recognizable. autocorrelation function leads to the Wigner distribution, and the interference terms that compromise its usefulness are discussed. Finally the reduced interference distributions SHORT TIME FOURIE