Constructing a wavelet-based envelope function for vibration signal analysis

In this paper, a wavelet-based envelope function derived from Morlet wavelet is proposed to apply in the envelope extraction for vibration signal. It is a complex function constructed by an orthogonal function pair. With a systematic method, the function parameters can be designated. From numerical implementation, it is found that the wavelet-based envelope function has the satisfactory properties of fast waveform convergence, constant passband gain and less phase distortion. For practical interest, the wavelet-based envelope function with 3-dB cut-off frequency is presented and carried out on an IBM compatible computer with a TMS320C32 DSP interface card. Finally, it is shown that the wavelet-based envelope function could be effectively applied in the vibration envelope extraction for a roller bearing system.