【摘要】 随着城市建设的不断发展,地磁场观测受到的人文干扰越来越严重.汽车、地铁、高铁等产生的近场噪音造成了地磁脉动等空间场源信号难以被精确观测,严重影响了地磁观测资料的实际使用价值.因此抑制这些近场噪音、提取空间场源信号具有科学意义和应用价值.本研究将远场参考法和盲源信号分离法相结合,提出了一种能有效分离空间场源信号和近场噪音的方法.首先,基于仿真分析,我们准确分离了不同特征的源信号,阐明了此方法的有效性.然后,我们将该方法应用于日本千叶地区受电车干扰较为严重的实际磁场观测数据,并选用数据质量较高的KAK国际基准台作为远场参考,实现了地磁脉动和电车干扰信号的分离,并在此基础上对观测台站的近场噪音进行了抑制.这些结果表明基于参考台的盲源信号分离法在抑制近场噪音、提取地磁场信号中是有效的,可能在电磁法勘探中具有潜在的应用价值.更多还原

【Abstract】 Along with the development of urban constructions,artificial disturbances in geomagnetic observations are becoming more and more tremendous.The near-field noises produced by human activities such as vehicles,subway and high-speed railways make it difficult to precisely measuregeomagnetic pulsations on the ground,thus reducing the practical application value of geomagnetic data.Therefore,suppressing near-field noises has scientific significance and application value.In this study,by combining remote reference and blind source separation analysis methods,we proposed a new signal processing approach which is able to separate geomagnetic pulsation from near-field noise.First,we demonstrated the effectiveness of the new approach by separating signals of different sources in the simulation analysis.Then,we applied this method to geomagnetic field data observed in Chiba,Japan where DC-driven train noises were intense.The results showed that geomagnetic pulsations and train noises are separated clearly,and near-field train noise could be reduced effectively on that basis.It is concluded that the reference-based blind source separation analysis is useful in extracting geomagnetic pulsations and suppressing near-field noises,and may have potential application value in electromagnetic exploration.更多还原