基于ANC与EMD的强电磁干扰下磁共振探测信号噪声抑制方法研究

项目名称： 基于ANC与EMD的强电磁干扰下磁共振探测信号噪声抑制方法研究

项目编号： No.41204079

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 地球物理学和空间物理学

项目作者： 田宝凤

作者单位： 吉林大学

项目金额： 25万元

中文摘要： 磁共振探测(MRS)技术作为一种直接探测地下水的地球物理方法，以其高分辨率、高效率、低成本等优点，被广泛应用于地下水资源探测与评价等领域。MRS信号极其微弱，对电磁噪声敏感成为该方法应用的主要局限。 项目针对MRS仪器在强电磁干扰下难以获得有效信号的瓶颈，研究自适应噪声抵消(ANC)联合经验模态分解(EMD)的噪声抑制方法。引入参考线圈，建立带参考通道的90度移相ANC系统，依变步长手段，实现不同信噪比下探测通道与参考通道相关噪声的抵消。为进一步提高信噪比，围绕EMD消噪算法中端点延拓、筛选停止条件及模态混叠问题，探讨适合于MRS信号与噪声特色的趋势项提取方法，实现非相关噪声去除。最后，通过实测数据和钻孔实验验证联合消噪方法的有效性。 本项目将解决强电磁干扰下MRS信号难以有效提取问题，提供一种切实可行的噪声抑制算法，拓展仪器使用范围，为我国水资源勘查与评价提供技术支持。

中文关键词： 磁共振测深；自适应噪声对消；经验模态分解；参考线圈；电磁噪声

英文摘要： Magnetic Resonance Sounding (MRS) technology is a geophysical method which allows a direct detection of groundwater. With its high resolution, high efficiency, low cost and other advantages, it has been widely used in groundwater exploration and evaluation. However, the main constraint of the method in application is the low level of MRS signal and it is sensitive to the electromagnetic noise. To get effective MRS signal within the strong electromagnetic interference, we propose this research for MRS signal noise cancellation by using Adaptive Noise Cancellation (ANC) and Empirical Mode Decomposition (EMD) methods. We initially introduce a reference coil and establish 90 degrees of channel phase shifting adaptive noise cancellation system. According to the variable step length means, it could achieve different signal-to-noise (SNR) detection channel and the related reference channel noise cancellation. In order to further improve SNR ratio, we also plan to study several algorithms of EMD, including endpoint continuation, screening stop conditions and modal aliasing of denoising. As a result, we could suggest a tendency item extraction method, which is appropriate suitable for MRS signal and noise characteristic to realize the related noise removal. Finally, the effectiveness of the combined methods can be veri

英文关键词： Magnetic resonance sounding；Adaptive noise cancellation；Empirical mode decomposition；Reference coil；Electromagnetic noise