Principal time constant map, a more accurate mapping tool for helicopter TEM data

Xiao, Pei; Wu, Xiaofeng; Shi, Zongyang; Guo, Rui; Pang, Yuxi; Fang, Guangyou

doi:10.1016/j.jappgeo.2018.08.001

Cited by 2 publications

(1 citation statement)

References 26 publications

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“…Taking the step pulse waveform with a ramp time of Δt as an example, the above formula can be rewritten as follows

where u(t) is the unit Heaviside function. In order to obtain the analytical solution of (10) and (12), we use an exponential model and equivalent circuit model to represent g 2 (t) and h(t), respectively [ 20 , 21 , 22 ], their transfer functions shape like

where A and τ are the amplitude and time constant of an exponential function, respectively, and ζ and w p are the damping coefficient and resonant frequency of the 2-order sensor system, respectively.…”

Section: Simulation Resultsmentioning

confidence: 99%

A New Weak-Coupling Method with Eccentric Dual Bucking Coils Applied to the PRBS Helicopter TEM System

Liu

Jiang

et al. 2022

Sensors

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In the helicopter transient electromagnetic system (HTEM), weak-coupling coils reduce the mutual inductance of the transmitting and receiving coils, which can protect the data acquisition circuit and improve the signal-to-noise of the system. The PRBS HTEM system is a newly proposed multi-receiver EM measurement system, which can effectively identify the system impulse response of the unknown geological model based on the high-precision synchronous recording signal of the PRBS emitted current and induced voltage. However, the standard PRBS current signal is turned on/off very quickly, easily resulting in signal saturation. Concerning this problem, this paper proposes a new weak-coupling structure named eccentric dual bucking coils for the multi-receiver EM system by analyzing the on/off characteristics of PRBS current and the magnetic field distribution of the transmitter–receiver system. It also verifies the feasibility of the proposed structure by Maxwell software simulation. Furthermore, considering the influence of the residual primary field and other factors, the data preprocessing results of the PRBS method and the traditional square wave method are compared by theoretical analysis and data simulation, and the results show that the earlier-time response data can be obtained by PRBS method under the same simulation conditions. Finally, the reliability of the proposed method is verified by ground experiment.

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“…Taking the step pulse waveform with a ramp time of Δt as an example, the above formula can be rewritten as follows

Section: Simulation Resultsmentioning

confidence: 99%

A New Weak-Coupling Method with Eccentric Dual Bucking Coils Applied to the PRBS Helicopter TEM System

Liu

Jiang

et al. 2022

Sensors

Self Cite

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The Development and Applications of the Helicopter-borne Transient Electromagnetic System CAS-HTEM

Fang

Xue

et al. 2019

JEEG

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Over the past decade, helicopter-borne transient electromagnetic (HTEM) systems have been rapidly developed. A new HTEM prototype (referred to as a CAS-HTEM) has been developed by the Chinese Academy of Sciences. In terms of hardware, the CAS-HTEM system uses an inflatable structure to carry the transmitting loop, which significantly reduces the weight of the system and makes it easier to transport. A dual gain receiver was innovated to extend the dynamic range of the system. In addition, an observation circuit for transmitting voltage waveform is introduced, so that the derivative waveform of transmitting current with higher SNR could be calculated. In terms of data processing, more reliable early time data could be obtained by band-limited effect removal; a weighted stacking algorithm is introduced to reduce the narrow band noise more effectively and increase the sensitivity of data to the anomaly location; a method based on τ-domain transform is used for late time signal processing. The results of the field test which was carried out in Inner Mongolia were found to be consistent with the drill data, which effectively verified the performance of this HTEM prototype.

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Principal time constant map, a more accurate mapping tool for helicopter TEM data

Cited by 2 publications

References 26 publications

A New Weak-Coupling Method with Eccentric Dual Bucking Coils Applied to the PRBS Helicopter TEM System

A New Weak-Coupling Method with Eccentric Dual Bucking Coils Applied to the PRBS Helicopter TEM System

The Development and Applications of the Helicopter-borne Transient Electromagnetic System CAS-HTEM

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