基于频谱分析识别电磁波信号干扰与地震异常
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摘要
处理北京地区2009—2012年5个高采样率数字CNEM08-Ⅰ型电扰动台站数据,通过频谱分析,研究数字电磁波正常本底信号,地铁、地电供电、电磁感应等干扰信号,以及地震异常信号的频谱特征。结果表明:在时间域,数字电磁波的持续型干扰信号与震前电磁波信号表现相似,为连续高值脉冲信号;而在频域,数字电磁波干扰信号往往影响频带较窄,优势频率能量突出,优势频率频带窄到近乎以谱线的形式出现,谱线具有离散性、谐波性、衰减性特征;而震前信号具有连续的较宽频带,衰减较慢。
In this paper,the spectrum characteristics of normal background signal,the subway interference,power supply interference,electromagnetic induction,and the seismic anomaly signal of the digital electromagnetic wave are studied through the spectrum analysis,based on the CNEM08-Ⅰ type digital electromagnetic wave data from 5 stations with high sampling rate at the Beijing area between 2009 and 2012.The results show that,in the time domain,the continuous interferences are very similar with the seismic anomaly signal.They are all continuous high value pulse signal.And in the frequency domain,digital electromagnetic interference signal often affects the narrow frequency bandwidth,the dominant frequency energy is very prominent and the bandwidth is narrow to spectral lines.The spectral lines jiave discrete,harmonic and attenuation characteristics.But the signals of seismic anomaly are continuous and have wide frequency bandwidth in general,the amplitude attenuation is slow.The different spectrum features will provide basis for identify interference and seismic anomaly of the digital electromagnetic wave based on the analysis of frequency domain.
In this paper,the spectrum characteristics of normal background signal,the subway interference,power supply interference,electromagnetic induction,and the seismic anomaly signal of the digital electromagnetic wave are studied through the spectrum analysis,based on the CNEM08-Ⅰ type digital electromagnetic wave data from 5 stations with high sampling rate at the Beijing area between 2009 and 2012.The results show that,in the time domain,the continuous interferences are very similar with the seismic anomaly signal.They are all continuous high value pulse signal.And in the frequency domain,digital electromagnetic interference signal often affects the narrow frequency bandwidth,the dominant frequency energy is very prominent and the bandwidth is narrow to spectral lines.The spectral lines jiave discrete,harmonic and attenuation characteristics.But the signals of seismic anomaly are continuous and have wide frequency bandwidth in general,the amplitude attenuation is slow.The different spectrum features will provide basis for identify interference and seismic anomaly of the digital electromagnetic wave based on the analysis of frequency domain.
引文
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郝建国,等.震前极低频电磁异常及其频谱特征[J].地震学报,1995,17(1):81-88.
李先吴,等.云南地区强震电磁波异常特征及其预报意义[J].地震,2003,23(2):76-84.
覃浩,等.用于谐波和间谐波检测的频谱分解法[J].现代电力,2012,29(4);36-40.
万永革.数字信号处理的Matlab实现[M].北京:科学出版社,2007:1-240.
周维合,等.着重探讨供配电系统中谐波的形成和抑制办法[J].大科技,2012,(6):78-79
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