分形分析与天然大地电磁场信号识别

由于大地电磁场信号的脉冲性质,对一定长度的时间序列进行相关性分析时将会导致这种相关性随着频率的增加几乎系统性地减小,因此采用相关分析识别大地电磁场信号存在固有的缺陷.利用相空间重构理论研究表明,大地电磁场信号的时间序列具有分形特征;通过天然场源与大地耦合关系,定义了一个新的识别大地电磁信号的新参数:“分形比”.实例分析结果表明,利用“分形比”识别信号比常用的相关性识别的方法更有效,估计的视电阻率曲线更为平滑、合理,曲线的形态也更为真实、可靠.

Fractal analysis and recognition of natural magnetotelluric field signal

The correlation of the natural magnetotelluric field signal in definite time-length sequences nearly decreases systematically with the increase of frequency because of the impulsive feature of the signal.Hence there is the shortcoming in the recognition of the signal by correlation analysis.In this paper,the study of the natural magnetotelluric field signal by means of phase space reconstruction theory shows that the time sequences of the signal is of fractal characteristics.A new parameter for the recognition of the natural magnetotelluric field signal ——"fractal ratio"—— is defined by the coupling of natural field with earth.The analysis result of a case indicates that the recognition of the natural magnetotelluric field signal by "fractal ratio" is more effective than by correlation analysis,and the estimated apparent resistivity curve is more smooth and reasonable,the shape of the curve is more real and reliable too.