Optimized Model Resolution Using Low Pass Filters in TDEM Soundings

Auken, Esben; Sørensen, Karsten Engsig; Thomsen, P.; Effersø, F.

doi:10.4133/1.2922778

Cited by 3 publications

(1 citation statement)

References 3 publications

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“…This is illustrated in Figure 3. The channels used to measure the earIy times have low gain, moderate bandwidth and narrow gates (Auken et al 2000), whereas the channels used to measure the late time signals have a higher gain, narrower bandwidth and wider gates. The instrument is designed in this way, because an real time gain adjustment is impossible at the early time gates.…”

Section: Receiver Systemmentioning

confidence: 99%

TDEM in Groundwater Mapping — A Continuous Approach

Sørensen¹,

Auken²,

Thomsen³

2000

Symposium on the Application of Geophysics to Engineering and Environmental Problems 2000

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Section: Receiver Systemmentioning

confidence: 99%

TDEM in Groundwater Mapping — A Continuous Approach

Sørensen¹,

Auken²,

Thomsen³

2000

Symposium on the Application of Geophysics to Engineering and Environmental Problems 2000

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A survey of current trends in near-surface electrical and electromagnetic methods

et al. 2006

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Electrical and electromagnetic ͑E&EM͒ methods for nearsurface investigations have undergone rapid improvements over the past few decades. Besides the traditional applications in groundwater investigations, natural-resource exploration, and geological mapping, a number of new applications have appeared. These include hazardous-waste characterization studies, precision-agriculture applications, archeological surveys, and geotechnical investigations. The inclusion of microprocessors in survey instruments, development of new interpretation algorithms, and easy access to powerful computers have supported innovation throughout the geophysical community and the E&EM community is no exception. Most notable are development of continuous-measurement systems that generate large, dense data sets efficiently. These have contributed significantly to the usefulness of E&EM methods by allowing measurements over wide areas without sacrificing lateral resolution. The availability of these luxuriant data sets in turn spurred development of interpretation algorithms, including: Laterally constrained 1D inversion as well as innovative 2D-and 3D-inversion methods. Taken together, these developments can be expected to improve the resolution and usefulness of E&EM methods and permit them to be applied economically. The trend is clearly toward dense surveying over larger areas, followed by highly automated, post-acquisition processing and interpretation to provide improved resolution of the shallow subsurface in a cost-effective manner.

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EMMA—A Geophysical Training and Education Tool for Electromagnetic Modeling and Analysis

Auken

Nebel

Sørensen

et al. 2002

JEEG

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An interactive modeling and analysis program with a user-friendly graphical interface, for students and professionals in the field of exploration geophysics, has been developed. The ElectroMagnetic Modeling and Analysis program-EMMA-is capable of modeling one-dimensional responses for most electrical and electromagnetic methods and array configurations, including the time-domain, frequency-domain, resistivity, magnetotelluric and borehole methods. EMMA is available on-line, at no charge, from http://www.hgg.au.dk.An innovation of EMMA is the calculation of the model sensitivity analysis, a feature that is usually only present in inversion codes. The variance of the model parameters depends on the variance of the measured data and the way in which an error is mapped from the data to the model parameters. The measurement situation is realized by ascribing data noise to the model response. This facilitates the calculation of a realistic model parameter analysis. For time-domain data, piecewise linear waveforms, ramps and low-pass filters are included in the forward modeling scheme.When implemented on a multi-user relational database structure, EMMA is suitable for classroom exercises where the computers are connected through a local network. As an illustration and for motivation, three exercises focusing on the time-domain electromagnetic method are presented: the mapping of noise to model resolution; the effect of filters on the early time response and layer resolution; and an examination of the electric and magnetic field intensity to understand the physical mechanisms of the method.Short courses on the subject of the transient electromagnetic and resistivity methods for hydrogeophysical investigations, offered to technical advisers and to technical policy-makers, have demonstrated EMMA's succes in providing a productive learning environment.

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Optimized Model Resolution Using Low Pass Filters in TDEM Soundings

Cited by 3 publications

References 3 publications

TDEM in Groundwater Mapping — A Continuous Approach

TDEM in Groundwater Mapping — A Continuous Approach

A survey of current trends in near-surface electrical and electromagnetic methods

EMMA—A Geophysical Training and Education Tool for Electromagnetic Modeling and Analysis

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