A Wavelet Transform Process For The Vibration Signal

In vibration test,the signal is always along with noise.If the noise belongs to white noise,fourier transform is very suit to identify and process it,after then remove it.But when there exists low energy impact signal,traditional band pass filter remove noise and the precise position of impact signal is blured.The time-frequency of the wavelet transform and the signal wavelet decomposition-reconstruction algorithm based on the multi-resolution analysis are analyzed.The signal local singularity under the wavelet transform are studied.The difference between between Mallat's Maximun Modulus algorithm and Donoho's waveshrink algorithm are analyzed,too.The denoise effect of different threshold and threshold function are studied.Base on Compare the advantage and disadvantage of Donoho&Johnstone threshold and believing-region threshold,a modified algorithm is developed: Combining threshold distinguishing and shield filter method. Lifting scheme is being used to decomposition-reconstruction signal,noise is removed and the precise position of impact signal is keeped.The signal-noise rate is improved,the loss is low.The method is very easy, many fields can apply it.