用时频分解法从空间波场中分离表面波信号

提出了一种从空间波场中分离表面波信号的方法，其基本原理是：在小波包变换和时域加窗对信号进行分解的时频单元上，通过改进的极化分析方法和构造的滤波函数对所有时频单元进行处理，将处理结果进行合成即可得到分离出的表面波．这种方法的优点是：对只在时间上重叠或只在频率上重叠的波，可进行有效的分离，压制了各向同性随机干扰，具有较高的时间频率分辨率；特别是通过改进的极化分析算法，可解决原方法中高阶模态表面波提取中存在的问题．

Separation of Surface Wave from Spatial Wave Field Based on Time Frequency Decomposition

A method is presented for separating the surface wave from the spatial wave field. Time frequency cell is used to decompose the signal using wavelet packet transform and time domain window. The data are processed through the improved polarization analysis method and filter function. The results are then synthesized to separate surface wave from the signal. Merits of method are: (1) only these waves overlapped in time or frequency can be processed effectively, (2) random and isotropic noises are suppressed, and (3) high time and frequency resolution are obtained. In particular, extracting surface wave with high order modes is made possible using the improved polarization analysis algorithm.