航空电磁数据主成分滤波重构的噪声去除方法  

Noise removal based on reconstruction of filtered principal components

作　　者：王凌群 李冰冰[1] 林君[1] 谢宾[1] 王琦[1] 程宇奇[1] 朱凯光[1] 

机构地区：[1]地球信息探测仪器教育部重点实验室,吉林大学仪器科学与电气工程学院,长春130026

出　　处：《地球物理学报》2015年第8期2803-2811,共9页Chinese Journal of Geophysics

基　　金：国家高技术研究发展计划项目(2013AA063904);国家自然科学基金项目(41274076);国家重大科研装备研制项目(ZDYZ2012-1-03)联合资助

摘　　要：主成分分析方法利用低阶主成分重构航空电磁数据,解决了航空电磁探测中噪声与数据在频谱重叠情况下的噪声压制问题,但是参与重构的低阶主成分仍包含高频空间噪声,影响数据成像精度.本文提出的主成分滤波重构去噪方法,根据自适应窗宽平滑算法,设计了主成分低通滤波器组,对参与重构的低阶主成分进行测线滤波,再将滤波后的低阶主成分重构为电磁信号,不仅可以去除低阶主成分中的高频空间噪声,而且去除了高阶主成分包含的不相关噪声.仿真数据的去噪结果表明,主成分滤波重构获得较高的信噪比,较常规测线滤波与主成分重构分别提高了10.96dB和2.52dB;电导率深度成像结果证明了主成分滤波重构方法能够提高地下深部异常体的识别能力.最后通过实测数据的成像结果进一步验证了本文研究的主成分滤波重构去噪方法的有效性.Airborne electromagnetic data has complex noise due to the flight environment,changes of system parameters and device parameters.The traditional time-frequency approach is difficult to remove noise.PCA（principal component analysis）can remove the noise which overlaps with the signal frequency spectrum.However the low-order components still contain high frequency spatial noise.To solve this problem,this work proposes the reconstruction of filtered principal components which can not only remove the high-frequency spatial noise of loworder components,but also remove uncorrelated noise of high-order components.This approach uses filtered principal components to reconstruct electromagnetic data.Firstly,it computes eigenvectors and eigenvalues matrix of the correlation matrix and the principal component profiles which are uncorrelated. The low-order principal components associated with the big eigenvalues reflect the correlated electromagnetic signals,while high-order principal components associated with the small eigenvalues are corresponding to the uncorrelated noise.It operates by first filtering the principal component profiles with the widest filter.Then according to local variation of each smoothed principal component profile,agroup of low-passfilters is designed.Local variation of each smoothed principal component profile is converted linearly into adaptive smoothing filter window width of the measuring point.So each principal component profile is filtered by the corresponding filter.Finally,filtered low-order principal components are used to reconstruct electromagnetic signal.This paper designed a pseudo-2Dearth model with a deep target.The noise added to it drowned the target of later channels and the CDI（conductivity depth imaging）cannot reflect the deep target.After PCA processing,principal component profiles of noise-contaminated data have high frequency spatial noise compared with those of the forward data.The peak to peak of noise amplitude of the first principal component is about 0.005nT/s.With a

关 键 词：时间域航空电磁 主成分 滤波重构 自适应窗宽 空间噪声 

分 类 号：P631[天文地球—地质矿产勘探]