Nonlinear Wavelet Packet Denoising of Impulsive Vibration Signals

In this paper an application is presented of the wavelet packet method for denoising of impulsive vibration signals. Vibration response of machines often includes signals with periodic excitation of resonances. The aim is to extract information regarding the physical mechanism which generates the impulsive characteristics of the signals. The signals are transformed using the wavelet packet method, and the resulting coefficients are nonlinearly modified. The reconstructed time waveform of the signal using the modified coefficients may reveal the impulsive characteristics, resulting in a safer identification of the source of the impacts. The approach and its parameters are evaluated on industrial signals resulting from defective bearings. Key-Words: wavelet packet, vibration , impulsive signal,denoising