地运动信号的时频分析

对实测地运动信号,分别应用短时傅里叶变换(STFT)、Wigner-Ville分布(WVD)、小波变换(WT)和Hilbert-Huang变换(HHT)进行了分析,讨论了地运动信号的时频分布.结果表明,地运动信号有多个中心频率,信号能量在0～30 Hz以内,优势频率在12～15 Hz.4种时频分析方法都能反映地运动信号的时频特征,STFT和WVD只能粗略反映信号能量的分布情况,可以给出能量峰值对应的具体时间和频率,但其分辨率单一.WT和HHT可以给出信号能量比较详细的分布情况,WT具有多分辨率特点,但给出的能量分布在一定的带宽内,不能给出某一频率的能量分布.HHT具有自适应性,给出的是某些特征分量的能量分布,也不能给出某一频率的能量分布.

Time -frequency analysis of ground motion signal

An experimental reco rding sig na l of g ro und motion w as analyzed by means of sho rt time Fourier t ransform ( ST FT ) , Wig ner-Ville dist ributio n (WV D) , w av elet t ransfo rm ( WT ) and Hi lbert-Hua ng t ransform ( HHT) . The time-f requency dist ributio n of the g round mo tion sig nal w as discussed. The resul ts show that the g round mo tion sig nal i s composed of sev eral f requencies, the energ y of the sig nal lies in 0-30 Hz, a nd the domina nt f requency i s 12-15 Hz. By analysis, fo ur mea ns can all ref lect the time-f requency characteristics o f the sig nal, but STFT and WV D co uld only giv e a simple time-f requency distribution of the signal, the analy zed result s f rom them wi th fix ed window function and sing le reso lv ing pow er can o nly giv e the time and f requency v aried w ith sig nal energ y peak v alues. W T and HHT can giv e a detailed timef requency di st ribution, the analyzed result s f rom W T wi th mul ti-reso lving pow er can ref lect the sig nal energ y dist ributio n v aried wi th certain f requency ba nd, how ev er, the result s can no t ref lect the sig nal energ y distribution at a certain f requency. The analy zed resul ts f rom HHT wi th self-adaptive characteristic can reflect the signal energ y dist ribution va ried wi th the intrinsic mode function, th ey also can not display the sig nal energy di st ributio n at a certain f requency.