正交多项式法在航空电磁运动噪声去除中的应用
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摘要
时间域航空电磁测量数据中常伴有表现出低频特性的运动噪声,其幅值远大于航空电磁探测系统的磁场强度,因此能否正确、高效地对其进行去除成为了时间域航空电磁数据预处理的关键问题。经过研究,本文采用正交多项式拟合方法对时间域航空电磁数据中的运动噪声进行去除。对数据中每个半周期时间序列利用正交多项式进行拟合,从而作差达到去除数据中运动噪声的目的。通过对理论数据和实测数据运动噪声去除的效果可以看出,正交多项式拟合方法可以有效的去除运动噪声,同时提升了航空电磁实测数据质量,提高了数据的信噪比。
Time domain airborne electromagnetic measurement data are often accompanied by motion noise with low-frequency characteristics,whose amplitude is much stronger than the magnetic field intensity of the airborne electromagnetic response. Therefore,whether it can be removed correctly and efficiently has become a key technology in the pre-processing of airborne electromagnetic data in time domain. In this paper,orthogonal polynomial fitting method is used to remove the motion noise of airborne electromagnetic data in time domain. The orthogonal polynomials fitting method is used to fit each half-cycle time series so as to remove the motion noise. It can be seen from the result of removing motion noise from simulation data and real data that orthogonal polynomials fitting method can effectively remove motion noise,improve the quality of airborne electromagnetic real data,and improve the SNR of data.
Time domain airborne electromagnetic measurement data are often accompanied by motion noise with low-frequency characteristics,whose amplitude is much stronger than the magnetic field intensity of the airborne electromagnetic response. Therefore,whether it can be removed correctly and efficiently has become a key technology in the pre-processing of airborne electromagnetic data in time domain. In this paper,orthogonal polynomial fitting method is used to remove the motion noise of airborne electromagnetic data in time domain. The orthogonal polynomials fitting method is used to fit each half-cycle time series so as to remove the motion noise. It can be seen from the result of removing motion noise from simulation data and real data that orthogonal polynomials fitting method can effectively remove motion noise,improve the quality of airborne electromagnetic real data,and improve the SNR of data.
引文
[1]李楠.时间域航空电磁数据预处理技术初探[D].长春:吉林大学,2010.Li N.Research on airborne time-domain electromagnetic data preprocessing[D].Changchun:Jilin University,2010.
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[7]尹大伟,林君,朱凯光,等.时间域航空电磁数据线圈运动噪声去除方法仿真研究[J].吉林大学学报:地球科学版,2013,43(5):1639-1645.Yin D W,Lin J,Zhu K G,et al.Simulation research on coil motion noise removal for time domain airborne electromagnetic data[J].Journal of Jilin University:Earth Science Edition(in Chinese),2013,43:1639-1645.
[8]王凌群,李冰冰,林君,等.航空电磁数据主成分滤波重构的噪声去除方法[J].地球物理学报,2015,58(8):2803-2811.Wang L Q,Li B B,Lin J,et al.Noise removal based on reconstruction of filtered principal components[J].Chinese J.Geophys.(in Chinese),2015,58(8):2803-2811.
[9]黎东升.时域地空电性源的三维电磁数值模拟及噪声抑制方法研究[D].长春:吉林大学,2016.Li D S.Three-Dimensional modeling of grounded electrical source airborne transient electromagnetic and reduction method of electromagnetic noise[D].Changchun:Jilin University,2016.
[10]Ji Y,Li D,Yu M,et al.A de-noising algorithm based on wavelet threshold-exponential adaptive window width-fitting for ground electrical source airborne transient electromagnetic signal[J].Journal of Applied Geophysics,2016,128:1-7.
[11]常锦才,赵龙,杨倩丽.基于正交多项式的数据拟合方法[J].河北理工大学学报:自然科学版,2011,33(4):79-84.Chang J C,Zhao L,Yang L Q.Data fitting method based on orthogonal polynomials[J].Journal of Hebei Polytechnic University:Natural Science Edition(in Chinese),2011,33(4):79-84.
[12]西永在,吴珊,廖桂香,等.时间域航空电磁响应数值模拟的精度分析[J].物探与化探,2014,38(6):1190-1194.Xi Y Z,Wu S,Liao G X,et al.Precision analysis of numerical simulation for time-domain airborne electromagnetic response[J].[J].Geophysical and Geochemical Exploration(in Chinese),2014,38(6):1190-1194.
[2]Lane R,Plunkett C,Price A,et al.Streamed data-a source of insight and improvement for time domain airborne EM[J].Exploration Geophysics,1998,29:16-23.
[3]Buselli G,Pik J,Hwang H.AEM noise reduction with remote referencing[J].Exploration Geophysics,1998,29:71-76.
[4]Macnae J C,Lamontagnet Y,West G F.Noise processing techniques for time-domain EM systems[J].Geophysics,1984,49:934-948.
[5]Munkholm M S.Motion-induced noise from Vibration of a moving TEM detector coil:characterization and suppression[J].Journal of applied Geophysics,1997,37:21-29.
[6]Lemire D.Baseline asymmetry,Tau projection,B-field estimation and automatic half-cycle rejections[R].Motreal:THEM Geophysics Inc,2001.
[7]尹大伟,林君,朱凯光,等.时间域航空电磁数据线圈运动噪声去除方法仿真研究[J].吉林大学学报:地球科学版,2013,43(5):1639-1645.Yin D W,Lin J,Zhu K G,et al.Simulation research on coil motion noise removal for time domain airborne electromagnetic data[J].Journal of Jilin University:Earth Science Edition(in Chinese),2013,43:1639-1645.
[8]王凌群,李冰冰,林君,等.航空电磁数据主成分滤波重构的噪声去除方法[J].地球物理学报,2015,58(8):2803-2811.Wang L Q,Li B B,Lin J,et al.Noise removal based on reconstruction of filtered principal components[J].Chinese J.Geophys.(in Chinese),2015,58(8):2803-2811.
[9]黎东升.时域地空电性源的三维电磁数值模拟及噪声抑制方法研究[D].长春:吉林大学,2016.Li D S.Three-Dimensional modeling of grounded electrical source airborne transient electromagnetic and reduction method of electromagnetic noise[D].Changchun:Jilin University,2016.
[10]Ji Y,Li D,Yu M,et al.A de-noising algorithm based on wavelet threshold-exponential adaptive window width-fitting for ground electrical source airborne transient electromagnetic signal[J].Journal of Applied Geophysics,2016,128:1-7.
[11]常锦才,赵龙,杨倩丽.基于正交多项式的数据拟合方法[J].河北理工大学学报:自然科学版,2011,33(4):79-84.Chang J C,Zhao L,Yang L Q.Data fitting method based on orthogonal polynomials[J].Journal of Hebei Polytechnic University:Natural Science Edition(in Chinese),2011,33(4):79-84.
[12]西永在,吴珊,廖桂香,等.时间域航空电磁响应数值模拟的精度分析[J].物探与化探,2014,38(6):1190-1194.Xi Y Z,Wu S,Liao G X,et al.Precision analysis of numerical simulation for time-domain airborne electromagnetic response[J].[J].Geophysical and Geochemical Exploration(in Chinese),2014,38(6):1190-1194.