The autocoherent spectrum: A useful spectral estimator for vibration analysis of rotating machinery. Accurate estimation and cancellation of pure tones

This paper describes a new spectral estimator based on the Fourier transform, the autocoherent spectrum (ACS), which enables the extraction of the pure sinusoidal components with a greater sensitivity-and an improved frequency resolution. It's statistical properties are studied, and it is shown how to remove pure tones in a spectrum, while keeping its broadband components. After detection of lines, their exact frequencies are computed by means of the autocoherent spectrum phase. Then, the amplitude and phase associated to each pure tone are determined from the Fourier transform of each sequence according to the exact frequency calculated and the weighting window used. The removal of the pure tones is then achieved by correcting the Fourier channels containing them, and also some neighbouring channels which are affected by the side-effects of the window used. (C) 1998 Academic Press.