Improving Medium Access in Through-The-Earth VLF-LF Communications

Bataller, V.; Muñoz, Antonio de Arriba; Gaudó, Pilar Molina; Mediano, Arturo; Cuchí, José Antonio; Villarroel, José Luis

doi:10.4304/jcm.4.4.284-294

Cited by 16 publications

(15 citation statements)

References 14 publications

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“…This impedance must be minimized in order to achieve the minimal possible influence in the earth impedance measurements, allowing more current to be injected into the earth and the detector electrodes to have low impedance values. Therefore, the optimal electrodes for the specific terrain are chosen according to previous experiments [Bataller et al, 2008]. They are also wetted with salty water reducing in that way its contact impedance.…”

Section: Earth Impedance Measurement Methodsmentioning

confidence: 99%

“…[27] The contact electrode model proposed by Gasulla has been found optimal for the type of electrode employed [Bataller et al, 2008]. The wire and contact impedance parameter values are estimated from measurements of the electrode contact impedance and total impedance between current electrodes, captured in the same experiment.…”

Section: Earth Impedance Measurement Methodsmentioning

confidence: 99%

“…models for the contact but many of them are not suitable for the application reported in this paper either due to the size of the electrodes or to the frequency range considered. The electrodes used in this study, steel rod electrodes, fit the Gasulla model [Gasulla, 1999], as demonstrated by Bataller et al [2008].…”

Section: Electrode Contact Impedancementioning

confidence: 99%

“…The inner diameter of the conductor varies between 0.8 (AWG 20) and 1 mm (AWG 18). The extended impedance of such a wire, Z w, presents an inductiveresistive series model [Bataller et al, 2008]. If the wire is coiled in a cable spool, a winding-dependent additional inductive component is added to the total impedance of the wire.…”

Section: Wire Impedancementioning

confidence: 99%

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Earth impedance model for through-the-earth communication applications with electrodes

et al. 2010

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[1] Through-the-earth (TTE) communications are relevant in applications such as caving, tunnel and cave rescue, mining, and subsurface radiolocation. The majority of the TTE communication systems use ground electrodes as load antenna. Wires, electrode contact, and earth impedances are the major contributors to the impedance observed by the transmitter. In this paper, state-of-art models found in the literature are reviewed, and an improved method to measure the earth impedance is presented. The paper also proposes an optimal circuit model for earth impedance between electrodes as a function of frequency, as a consequence of the particular conditions of the application. The model is validated with measurements for different soil conditions, showing a good agreement between empirical data and the simulation results.

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Section: Earth Impedance Measurement Methodsmentioning

confidence: 99%

Section: Earth Impedance Measurement Methodsmentioning

confidence: 99%

Section: Electrode Contact Impedancementioning

confidence: 99%

Section: Wire Impedancementioning

confidence: 99%

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Earth impedance model for through-the-earth communication applications with electrodes

et al. 2010

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“…Therefore, it is difficult, inconvenient, and costly to place noise-reference sensors remotely when communicating. Further, sensors such as loop antennas [1,6], air coils, and electrodes [7,8] are unsuitable for placement in underground or underwater terrains, especially during emergencies [9]. This is because air coils or loop antennas need to be large (such as these loop diameters of 3.8, 12.5, 26, and 90 m [1]) to obtain high sensitivity required for receiving weak magneticfield signals, and the receiving terminals of the electrodes need to be separated over a large distance.…”

Section: Introductionmentioning

confidence: 99%

Design of the Magnetic Field Sensing System for Downlink Signal Reception and Interference Cancelling for Through-the-Earth Communication

Zhao¹,

Jiang²,

Zhang³

et al. 2016

Journal of Magnetics

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A magnetic field sensing system with a single primary sensor and multiple reference sensors deployed locally and orthogonally, was proposed for downlink signal reception and interference cancelling for Through-theEarth Communication (TEC). This paper mathematically analyzes a design optimization process for a search coil magnetometer (SCM), and applies that process to minimize the bandwidth of the primary SCM for TEC signal reception and the volume of reference SCMs for multiple distributions. The primary SCM achieves a 3-dB bandwidth of 7 Hz, a sensitivity threshold of 120 fT/√Hz, and a volume of 2.32 × 10 −4 m 3 . The entire sensing system volume is as small as 10 −2 m 3. Experiments with interference from industrial frequency harmonics demonstrated an average of 36 dB and 18 dB improvements in signal-to-interference ratio and signal-tointerference plus noise ratio, respectively, using multichannel recursive-least-squares algorithm. Thus, the proposed sensing system can reduce the interference effectively and allows reliable downlink signal reception.

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A Review of the Applications of Through-the-Earth (TTE) Communication Systems for Underground Mines

Ngwenyama,

Webber-Youngman

2024

Mining, Metallurgy & Exploration

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Underground mining accidents have the potential of leaving miners trapped in unknown and life-threatening locations for an extended period of time. The lives of the trapped and unaccounted-for miners are at risk and require emergency rescue. But, the primary tracking systems are highly susceptible to damage during accidents and are most likely to be defunct and inoperable post-accident. This prompted the need for a robust and reliable post-accident communication and locator system. Subsequently, the through-the-earth (TTE) communication systems were developed and tested in underground mines. Under ideal conditions, these systems are capable of post-accident full-duplex two-way voice, text, and data communication and fingerprint detection of the geolocations of the trapped miners. This is achieved through a wireless link established by the transmission of electromagnetic and seismic waves between surface and underground, even in challenged underground environments. Unlike the primary tracking systems, the TTE communication systems do not require extensive shaft-to-workplace backbone infrastructure. This has made the TTE systems to be less susceptible to damage and therefore suitable for post-accident communication. Instead, the Earth’s crust acts as the signal transmission medium which forms an uplink and downlink communication path. This is achieved by injecting an electric current into the ground using electrodes, by transmitting magnetic fields from a radiating loop antenna, or by inducing fingerprint geolocations using seismic waves. Range and data rates are the critical requirements for the effectiveness of these systems and are dependent on factors such as the antenna design, frequency, and rock properties. This study provides a review of the applications of the different types of TTE communication systems, their evolution, factors that affect them, and techniques for improving their efficiencies and capabilities. These systems present the mining industry with an opportunity to improve safety by providing post-accident communication and locating trapped miners as quickly as possible. This will improve their survival chances and ultimately reduce fatality rates in the mining industry.

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Improving Medium Access in Through-The-Earth VLF-LF Communications

Cited by 16 publications

References 14 publications

Earth impedance model for through-the-earth communication applications with electrodes

Earth impedance model for through-the-earth communication applications with electrodes

Design of the Magnetic Field Sensing System for Downlink Signal Reception and Interference Cancelling for Through-the-Earth Communication

A Review of the Applications of Through-the-Earth (TTE) Communication Systems for Underground Mines

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