摘要
为研究小波基及阈值参数选择对瞬变电磁数据去噪效果的影响,分析阈值去噪原理,针对改进的阈值去噪函数,选取Bior 2.4,Sym 6,Db 4和Coif 3常用小波基分别处理受干扰的瞬变电磁数据,结合各测点信噪比和最小均方差,实现并自动筛选出针对各测点最优去噪小波基和最佳阈值参数,结合工程实例分析验证各种处理效果。结果表明不同小波基对瞬变电磁受干扰的数据阈值去噪结果不同,单一小波基降噪并不适用所有测点,但阈值函数中不同参数对去噪效果影响很小;结合地质资料和钻孔资料,对比分析只变化小波基时改进的时阈值函数处理后绘制的视电阻率-深度断面可知,自动筛选最优小波基去噪效果与实际最相符。因此,使用改进的阈值去噪函数对瞬变电磁受干扰的数据去噪时,建议考虑小波基的不同对去噪效果的影响,合理选择针对每个测点适合的小波基以达到最佳去噪效果。
In order to examine the influence of wavelet base and threshold parameter selection on the denoising effect of transient electromagnetic data,the principle of threshold de-noising is analyzed firstly.For the improved threshold de-noising function,the four commonly-used wavelet bases of Bior 2.4,Sym 6,Db 4 and Coif 3 were chosen to process the disturbed transient electromagnetic data respectively,and the combination of the parameters in the threshold function under a single wavelet basis for noise reduction processing,followed by the change of the signal-to-noise ratio and the minimum mean square error of each measurement point.Through programming,the optimal de-noising wavelet bases and optimal threshold parameters for each measuring point are automatically screened out at the same time.Finally,the effects of various processing methods are illustrated and verified with examples.The results show that the data threshold de-noising results of different wavelet bases for transient electromagnetic interference are different.Single wavelet base noise reduction is not applicable to all measurement points,but different parameters in the threshold function have little effect on the de-noising.Combining the geological data and the drilling data,an analytical comparison has been made of the apparent resistivity-depth profile drawn after the improved time-threshold function of the wavelet-based modified time.The de-noising effect of the automatic screening of the optimal wavelet base is the best.Therefore,when using the improved threshold de-noising function to de-noise the transient electromagnetic interference data,it is recommended to take the de-noising effects of different wavelet based into consideration,and to make a reasonable selection of the suitable wavelet base for each measuring point to achieve the best noise effect.
作者
解海军
李静蕊
董毅
李进
孙展雄
XIE Hai-jun;LI Jing-rui;DONG Yi;LI Jin;SUN Zhan-xiong(College of Geology and Environment,Xi’an University of Science and Technology,Xi’an 710054,China;Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation,Xi’an 710054,China;School of Geoscience and Surveying Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)
出处
《西安科技大学学报》
CAS
北大核心
2020年第4期682-690,共9页
Journal of Xi’an University of Science and Technology
基金
国家自然科学基金(41472234)。
关键词
小波基
阈值参数
瞬变电磁
去噪效果
wavelet basis
threshold parameter
transient electromagnetic
de-noising effect
