De-noising of the raw vibration signal is essential requirement to improve the accuracy and efficiency of any fault diagnosis of method. In many cases the noise signal is even stronger than the actual signal, so it is important to have such system in which noise elimination can be done effectively, there are many time domain and frequency domain methods are already available, where use of wavelet as time-frequency domain method in the field of de-noising the vibration signal is relatively new, it gives multi resolution analysis in both is time-frequency domain. In this paper various conventional thresholding methods based on discrete wavelet transform are compared with adaptive thresholding method and Penalized thresholding method for the de-noising of vibration signal of rotating machine. Signal to noise ratio (SNR), root mean square error (RMSE) in between de-noised signal with original signal are used as an indicator for selecting the effective thesholding method.
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