Research of Time-frequency Analysis Method of Nonstationary Periodic Signal

Nonstationary periodic signal(NPS) is a sort of stochastic signal whose period follow normal distribution, and the statistic average value of period (SAVT) of NTS is very important but difficult to yield. Several time-frequency analysis method including short time power spectrogram(STPS), Wigner-Ville distribution(WVD) and wavelet transform(WT) are employed to obtain the SAVP of NIPS, then Gauss white noise and color noise with large amplitude are used to verify the anti-interference capability of these methods. The analytic results show that STPS with inertia filtering can separate NTS from noise efficiently and has good time-frequency resolution of NPS, which means high measurement precision of SAVP. Smooth pseudo Wigner-Ville Distribution (SPWVD) and redistribution SPWVD have excellent time-frequency aggregation and resolution, but their anti-interference capability is a flaw. WT has powerful ability of anti-disturbance. In sum, all the three methods can compute SAVP of NPS, among them, STPS and WVD have higher measurement precision while WT has more perfect dynamic characteristic.