Hilbert-Huang变换对FGM-01地磁观测资料的噪声抑制

NOISE SUPPRESSION OF FGM-01 GEOMAGNETIC OBSERVATION DATA BY HILBERT-HUANG TRANSFORM

采用Hilbert-Huang变换对磁暴干扰下的乌鲁木齐台和温泉台FGM-01数据进行分析,探讨在地磁信号处理及噪声压制中的应用。实验首先利用HHT变换的EMD分解对地磁FGM-01信号进行分解,得出地磁信号EMD分解后的各阶IMF信号。通过对各阶IMF信号的频谱分析可得:第4阶IMF信号的能量与原地磁信号的能量相对应,能量均集中在0.1 Hz之内,干扰表现最为明显。实验将第4阶IMF干扰信号进行抑制后重构地磁信号,结果表明乌鲁木齐台FGM-01数据Z分量的SNR(信噪比)为29.74 dB;H分量的SNR为7.61 dB;D分量的SNR为7.14 dB。温泉台FGM-01数据Z分量的SNR为22.03 dB;H分量的SNR为15.89 dB;D分量的SNR为12.92 dB。经过HHT变换分析及噪声压制后,地磁FGM-01信号各分量的SNR均得到了提高。实验在一定程度上消除了磁暴噪声干扰,突出了地磁FGM-01的有用信息,提高了地磁观测资料的应用效果。

Hilbert Huang transformation is used to analyze Urumqi station and Wenquan station FGM-01 data under the disturbance of magnetic storm, and its application in geomagnetic signal processing and noise suppression is discussed. Firstly, the EMD decomposition of HHT transform is used to decompose the geomagnetic FGM-01 signal, and the IMF signals of the geomagnetic signal EMD are obtained. Through the spectrum analysis of the IMF signals of various orders, it can be obtained that the energy of the fourth-order IMF signal corresponds to the energy of the original geomagnetic signal. The energy is concentrated within 0.1 Hz and the interference performance is most obvious. The experiment reconstructs the geomagnetic signal after suppressing the fourth-order IMF interference signal. Based on data of Urumqi station, the experimental results show that the SNR of Z component is 29.74 dB;the SNR of H component is 7.61 dB;and the SNR of D component is 7.14 dB. Based on data of Wenquan station, the experimental results show that the SNR of the Z component is 22.03 dB;the SNR of the H component is 15.89 dB;and the SNR of the D component is 12.92 dB.The experimental results show that the SNR of each component of geomagnetic FGM-01 signal is improved after HHT transform analysis and noise suppression.The experiment eliminates the magnetic storm noise interference to a certain extent and highlights the useful information of the geomagnetic FGM-01.The experiment improves the application effect of geomagnetic data.