地学前缘 ›› 2016, Vol. 23 ›› Issue (1): 275-286.DOI: 10.13745/j.esf.2016.01.025

• 非主题来稿选登 • 上一篇    

基于NSTFT-WVD变换的芦山MS 7.0级地震前后地球天然脉冲电磁场信号时频分析

郝国成，陈忠昌，赵娟   

  1. 1. 中国地质大学(武汉) 机械与电子信息学院, 湖北 武汉 430074
    2. 教育部三峡库区地质灾害研究中心, 湖北 武汉 430074
    3. 中国地质大学(武汉) 地球科学学院, 湖北 武汉 430074
    4. Environmental Center for Resources Conservation, Krasnoyarsk 660049, Russia
  • 收稿日期:2015-07-28 修回日期:2015-11-13 出版日期:2016-01-15 发布日期:2016-01-15
  • 通讯作者: 赵娟(1978—)，女，博士，讲师，主要从事信息、图像处理研究。E-mail：1150978143@qq.com
  • 作者简介:郝国成(1975—)，男，博士，硕士生导师，讲师，主要从事信息处理、地球天然脉冲电磁场研究。E-mail：haogch@cug.edu.cn
  • 基金资助:

    国家自然科学基金项目(41502281)；中国博士后科学基金项目(2015M582293)；湖北省自然科学基金面上项目(2014075101)；中国地质大学(武汉)实验技术研究项目(SJ - 201423)

Timefrequency analysis of the Earths natural pulse electromagnetic field signal before and after the Lushan MS 7.0 earthquake based on NSTFTWVD transform.

  • Received:2015-07-28 Revised:2015-11-13 Online:2016-01-15 Published:2016-01-15

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摘要：

本文针对地球天然脉冲电磁场(ENPEMF)信号的非平稳性特点，通过采用归一化STFT - WVD变换(NSTFT - WVD)提取芦山MS 7.0地震前地表天然脉冲电磁场信号的时频特性，来研究大地震发生前地表天然脉冲磁场的时频特点。通过对线性调频信号分别进行Short Time Fourier Transform(STFT)和Wigner Ville Distribution(WVD)，对比分析两者时频聚集的优缺点，提出采用NSTFT - WVD变换方法，可得到时频聚集特性更优且可抑制交叉项的时频分析方法。结果表明，对于ENPEMF非平稳信号，NSTFT - WVD变换能较为真实地反映震前ENPEMF信号的时频能量谱的联合分布特性，即震前1~2天呈现较为明显的脉冲全频率段静默状态，通道2和通道3数据的震前时频表现基本一致，具有较好的临震前兆的特点。

关键词: 地震, 地球天然脉冲电磁场(ENPEMF), NSTFT-WVD变换, 抑制交叉项, 时频分析

Abstract:

The present paper aims at the nonstationary characteristics of Earths natural pulse electromagnetic field (ENPEMF) signals by using the normalized STFT - WVD(NSTFT - WVD) transformation, and the main analysis focuses on timefrequency characteristics of the ENPEMF signal before Lushan MS 7.0 earthquake. By comparing shorttime Fourier transform(STFT)and WignerVille distribution(WVD)transformation with the linear frequency modulation signal, this paper analyzes their advantages and disadvantages of both time and frequency focusing performance. NSTFT - WVD transform method can give us the better timefrequency aggregation and inhibits the cross terms. The results show that NSTFT - WVD transform can reflect the real ENPEMF signal timefrequencyenergy spectrum distribution before and after the earthquake, which could render more obvious silent state in entire frequency and sustained 12 days before the earthquake. The timefrequency representation of data channels 2 and 3 are basically consistent with this characteristic, which well represents the feature of impending earthquake precursors.

Key words: earthquake, the Earths natural pulse electromagnetic fields(ENPEMF), Normalized STFTWVD (NSTFTWVD), crossterm suppression, timefrequency analysis

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