航空电磁探测的运动噪声时频特征分析
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摘要
针对航空电磁探测系统由于姿态角度变化引入运动噪声的问题,提出了一种用于降噪去噪的时频特征分析方法。在法拉第电磁感应定律的理论基础上,仿真了姿态角引起的运动噪声的时、频谱图,分析了姿态角与运动噪声在时域和频域中的相关性。采用Gabor变换的时频分析方法,研究了姿态角产生的运动噪声对电磁响应的影响,从幅度关系上剖析了姿态角度与运动噪声的关联,对运动噪声和姿态角与其导数在不同频率点的相关性进行对比可知,与姿态角本身相比,其一阶导数对运动噪声的影响更显著。
The motion noise is introduced by the change of the attitude angle,which affects the consistency of the observed data due to the influence of the flight attitude,velocity and temperature conditions of the aeronautical electromagnetic detection system. Based on Faraday Law of Electromagnetic Induction,the spectrum of the motion noise caused by the attitude angle is simulated.The correlation between the attitude angle and the motion noise is analyzed in time domain and the frequency domain.The time-frequency analysis method of Gabor transform is used to study the influence of motion noise generated by attitude angle on the electromagnetic response. The relationship between the attitude angle and the motion noise is analyzed from the amplitude.Comparison of the correlation of different frequencies shows that the effect of the derivative on the motion noise is more serious than the attitude angle itself.
The motion noise is introduced by the change of the attitude angle,which affects the consistency of the observed data due to the influence of the flight attitude,velocity and temperature conditions of the aeronautical electromagnetic detection system. Based on Faraday Law of Electromagnetic Induction,the spectrum of the motion noise caused by the attitude angle is simulated.The correlation between the attitude angle and the motion noise is analyzed in time domain and the frequency domain.The time-frequency analysis method of Gabor transform is used to study the influence of motion noise generated by attitude angle on the electromagnetic response. The relationship between the attitude angle and the motion noise is analyzed from the amplitude.Comparison of the correlation of different frequencies shows that the effect of the derivative on the motion noise is more serious than the attitude angle itself.
引文
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[3]吴勇.直升机时间域电磁系统吊舱振动噪声分析与仿真测试研究[D].长春:吉林大学仪器科学与电气工程学院,2014.Wu Yong.Noise analysis and simulation test research for pod vibration of helicopter-borne TEM system[D].Changchun:College of Instrumentation and Electrical Engineering,Jilin University,2014.
[4]Macnae J C,Lamontagne Y,West G.Noise processing techniques for time-domain EM systems[J].Geophysics,1984,49(7):934-948.
[5]Lane R,Green A,Golding C,et al.An example of3Dconductivity mapping using the TEMPEST airborne electromagnetic system[J].Exploration Geophysics,2000,31:162-172.
[6]Buselli G,Hwang H S.AEM noise reduction with remote referencing[J].Exploration Geophysics,1998,29:71-76.
[7]Munkholm M S.Motion-induced noise from vibration of a moving TEM detector coil:characterization and suppression[J].Journal of Applied Geophysics,1997,36:21-29.
[8]Danvis A C,Macnae J,Robb T.Pendulum motion in airborne HEM system[J].Exploration Geophysics,2006,37:355-362.
[9]Kass M A,Li Y,Krahenbuhl R,et al.Enhancement of TEM data and noise characterization by principal component analysis[R].Douglas Oldenburg:Department of Geophysics,Colorado School of Mines,2010.
[10]王琦,林君,于生宝,等.固定翼航空电磁系统的线圈姿态及吊舱摆动影响研究与校正[J].地球物理学报,2013,56(11):3741-3750.Wang Qi,Lin Jun,Yu Sheng-bao,et al.Study on influence and correction of coil attitude and bird swing for the fixed-wing time-domain electromagnetic system[J].Chinese Journal of Geophysics,2013,56(11):3741-3750.