Review of three airborne EM systems

Mulè, Shane; Miller, R. B.; Carey, Heather; Lockwood, Ray

doi:10.1071/aseg2012ab352

Cited by 14 publications

(5 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The time-domain transient electromagnetic method (TEM) typically employs two different multi-turn coils: the TX coil in the transmitter and the RX coil in the receiver. The former transmits the time-varying current to generate the primary electromagnetic field and the latter receives the secondary field-induced voltage generated from the eddy currents of subsurface conductors [ 5 , 6 ]. TEM systems are very effective in geological detection [ 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Detection System with Magnetic Dipole Source for Near-Surface Detection

Liao,

Xu,

Liu

et al. 2023

Sensors

View full text Add to dashboard Cite

This paper proposes a nondestructive, separate transmitter-receiver (TX-RX) electromagnetic measurement system for near-surface detection. Different from the traditional dual-coil integrated design, the proposed transient electromagnetic (TEM) system performs shallow subsurface detection using independent TX coil and movable RX coils. This configuration requires a large primary field so that the far-away secondary field is able to generate reliably induced voltages. To achieve this goal, a bipolar current-pulsed power supply (BCPPS) with a late resonant charging strategy is designed to produce a sufficiently large magnetic moment for the exciting coil with low source interference. The magnetic dipole source (MDS) with a large proportion of weight is separated from the field observation device and does not need to be dragged or transported during the detection process. This setup lowers the weight of the scanning device to 3 kg and greatly improves the measurement efficiency. The results of the laboratory test verify the effectiveness of the separate MDS and RX module system. Field experimental detection further demonstrates that the proposed system can realize highly efficient and shallow surface detection within a 200 m range of the MDS device.

show abstract

Section: Introductionmentioning

confidence: 99%

Electromagnetic Detection System with Magnetic Dipole Source for Near-Surface Detection

Liao,

Xu,

Liu

et al. 2023

Sensors

View full text Add to dashboard Cite

show abstract

“…With the rapid development of modern software and hardware technology, a variety of electric and electromagnetic geophysical methods are widely applied to different exploration purposes (Auken et al., 2015; Mulè et al., 2012). Due to its advantages of high detection efficiency and large penetration depth (Legault et al., 2018; Reid et al., 2010), the airborne transient electromagnetics (AEM) method has attracted more and more attention and favour from industry personnel.…”

Section: Introductionmentioning

confidence: 99%

An efficient 2.5‐D forward algorithm based on the spectral element method for airborne transient electromagnetics data

Liu

Huang

et al. 2023

Geophysical Prospecting

View full text Add to dashboard Cite

The airborne transient electromagnetics method has been widely used in geophysical exploration in recent years, but it still faces challenges in balancing the accuracy and efficiency of electromagnetic data interpretation. As far as forward modelling is concerned, the higher the dimension of the geophysical model, the higher the accuracy of data interpretation, but, correspondingly, the more computing resources need to be consumed, which will greatly reduce investigation efficiency and practicability. In this paper, the spectral element method is first introduced for solving the 2.5-dimensional forward modelling of the airborne transient electromagnetic system, which has a smaller computing scale than three-dimensional modelling and is closer to the actual geological structure than either one-or two-dimensional modelling. In the forward algorithm, a non-uniform quadrilateral structured mesh is adopted to simplify the computing scale, and the Talbot algorithm rather than Gaver-Stefest algorithm is applied to the inverse Laplace transform to improve the numerical precision of this conversion. Moreover, we use parallel computing technology to improve the algorithm efficiency while keeping satisfactory accuracy. The study shows that, whether a low-resistivity or high-resistivity layered geophysical model, the numerical solutions of the proposed spectral element method forward algorithm agree well with the analytical solutions of the corresponding models; furthermore, the key factors affecting the accuracy of the numerical solution are analysed by experiments. Finally, we successfully applied it to the 2.5-dimensional geoelectric model simulation.

show abstract

“…The Transient Electromagnetic, TEM method is a well-known and well-accepted technology utilized in reservoir exploration, groundwater mapping, saltwater boundary mapping, and a variety of other applications (Auken et al, 2017;Law et al, 2019;Chen et al, 2020). TEM surveys can be done using ground-based instruments that are moved manually between measurements or instruments mounted on mobile platforms such as fixed-wing aircrafts and helicopters, or towed behind all-terrain vehicles (Mulè et al, 2012;Auken et al, 2019;Liu et al, 2019;Chen et al, 2022). Moving systems are a cost-effective solution with high spatial resolution and allows for large-area mapping.…”

Section: Introductionmentioning

confidence: 99%

An Optimized and Hybrid Gating Scheme for the Suppression of Very Low Frequency Radios in Transient Electromagnetic Systems

Khare,

McLachlan,

Maurya

et al. 2023

Preprint

View full text Add to dashboard Cite

Abstract. One of the most used approaches for measuring the earth's subsurface resistivity is the transient electromagnetic method (TEM). However, noise and interference from different sources, e.g., radio communication, the instrument, the atmosphere, and powerlines severely taint these types of signals. In particular, radio transmission in the very low-frequency (VLF) range between 3 kHz and 30 kHz is one of the most prominent sources of noise. Transient electromagnetic signals are normally gated to increase the signal-to-noise ratio. A precise selection of gate shapes is required to suppress undesired noise while allowing the TEM signal to pass unaltered. We employ the multi-objective particle swarm optimization technique to choose optimal gate shapes and placements by minimizing an objective function composed of standard error bars, the covariance between gates, and the distortion of the gated signal. The proposed method is applied to both fully sampled synthetic TEM data and to boxcar-gated field data. The best output from the search space of gate shapes was found to be a hybrid combination of boxcar and Hamming gates. The effectiveness of hybrid gating over traditional boxcar and semitapered gating is confirmed by an analysis of covariance matrices and error bars. The results show that the developed method effectively suppresses VLF noise in the middle gates, that is, gates with center times spanning 30 µs to 200 µs and in the late gates, that is, gates with center times spanning 200 µs to 1130 µs. The analysis shows that the average improvement in standard errors obtained for the hybrid gating scheme over boxcar gating is 1.719 and 1.717 on synthetic and field data, respectively.

show abstract

Review of three airborne EM systems

Cited by 14 publications

References 5 publications

Electromagnetic Detection System with Magnetic Dipole Source for Near-Surface Detection

Electromagnetic Detection System with Magnetic Dipole Source for Near-Surface Detection

An efficient 2.5‐D forward algorithm based on the spectral element method for airborne transient electromagnetics data

An Optimized and Hybrid Gating Scheme for the Suppression of Very Low Frequency Radios in Transient Electromagnetic Systems

Contact Info

Product

Resources

About