Chirplet变换中的参数选择研究

针对参数选取不当时Chirplet变换结果无法有效表征信号的时频特性，提出了根据待分析信号特点恰当选取Chirplet变换中各参数的方法．与修正Chirplet变换中的参数选取方法不同，该方法将伸缩因子的选取转化为构造目标函数求解最优化问题来解决．最优伸缩因子与时间、频率上的线性调频率有关，应用恰当选取的时间、频率上的线性调频率及将两者作为输入选取的最优伸缩因子，可使Chirplet变换结果具有较高的时频分辨率．采用所提方法分析两个Chirp的线性叠加信号及合成地震沉积旋回信号，在时频平面可以清晰地辨别应用短时傅里叶变换和小波变换所不能区分的两个Chirp信号，并且更精细地刻画了沉积旋回的韵律．新方法为用地震资料进行沉积旋回分析及储层研究提供了一个有力的工具．

On the Choice of Parameters for the Chirplet Transform

Considering that the Chirplet transform(CT) results can not efficiently present the time-frequency(TF) representations of a signal without suitable parameters,a measurement method was proposed on how to choose the optimal values of parameters of the Chirplet transform for the signal to be analyzed.Different from the method used in the modified Chirplet transform,in our method the problem of the scale parameter selection is transformed into that of parameters optimization.The best scale parameter depends on the input of the chirp rate both in time and frequency.Suitable choose of the two parameters as input can get the best scale parameter.With these three parameters the Chirplet transform results will have much higher TF resolution.The dual-component chirp signals and the seismic sedimentary signal are analyzed with this method,and it is found that in the TF plane the two Chirp signals can be clearly presented which can not be distinguished by the short-time-Fourier-transform and the wavelet transform,and the rules of rhyming of the sedimentary signal can be exactly depicted.This shows that the method is a powerful tool for the sedimentary signal analysis using the seismic data.