Designing digital linear filters for computing resistivity and electromagnetic sounding curves

Author:

Das U. C.1

Affiliation:

1. National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, India

Abstract

Ghosh’s method of designing filters (1970, 1971a, b) for computing apparent resistivity and electromagnetic (EM) sounding curves over a layered earth requires a set of known input and output functions satisfying the corresponding convolution integral. The spectrum of the filter in amplitude |H(f)| and in phase φ(f) is determined as [Formula: see text], [Formula: see text], respectively. Inverse Fourier transform of the spectrum results in the filter function, which is sampled to derive the filter coefficients. For different electrode or coil configurations, different sets of input‐output functions are chosen. The criteria for choosing them were given in Koefoed et al (1972) and Anderson (1975). An alternative method of designing a filter was given by Johansen and Sørensen (1979) who obtained an explicit series expansion for the filter function and handled the tail of the infinite summation analytically. Following Ghosh’s method, Anderson (1979) designed the filters for Hankel transforms of orders 0 and 1 where both filters have identical abscissas. This avoids repetitious kernel evaluations because the kernels of many of the integral transforms of orders 0 and 1 encountered in electrical prospecting are related to one another by simple algebraic relationships. Table 1 presents a 14‐point filter (six intervals per log decade; abscissa of the filter coefficient [Formula: see text] is +0.1343155) designed by the author for Schlumberger curve computation.

Publisher

Society of Exploration Geophysicists

Subject

Geochemistry and Petrology,Geophysics

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3