A Method and Application of Signal Demodulation Based on Wavelet Packet and Wavelet Ridge Decomposition

Vibration signals are non-stationary and nonlinear in rotating machinery. Aiming at this phenomenon, a demodulation approach based on wavelet packet decomposition and Wavelet Ridge was proposed in this paper. The frequency range where energy was concentrated in was acquired through the power spectrum of fault vibration signal. Then the number of layers decomposed by the wavelet packet was determined, according to the determinate bandwidth. And the wavelet packet energy method was used to ascertain the frequency band containing the most energy. Afterwards the corresponding decomposition coefficients were extracted to reconstruct the signal. Moreover, the Wavelet Ridge method was employed to demodulate the reconstructed signal. The fault characteristic frequency was effectively extracted from envelope spectrum and utilized to judge the working conditions and fault type. At last, a deeply analyze on fault signals of bearing inner ring and outer ring was carried out. Results show that this proposed method can effectively extract the characteristic frequency of fault signal.