Through-the-Earth, Two-Way, Mine Emergency, Voice Communication Systems

Zhang

2010

J Coal Sci Eng China

Based on the Wireless Mesh Network (WMN), a wireless emergency communication system for underground coal mine which was designed to be capable of video surveillance, voice communication, and environment monitoring at the same time was proposed. The network architecture of the system was proposed, and its service model, extensible technology, medium access control, routing algorithm, channel allocation and system management technologies were analyzed according to the actual rescue requirements of underground coal mine and the characteristics of underground spatial structure and radio transmissions. The relevant theories and key technologies were extracted, which would provide theoretical support for the system development.

Section: Research Statusmentioning

confidence: 96%

Constructing of wireless emergency communication system for underground coal mine based on WMN technology

Zhang

2010

J Coal Sci Eng China

Antennas Wirel. Propag. Lett.

“…Moreover since MI technique relies on magnetic fields rather than electromagnetic waves, its transmitters and receivers (which are essentially coil inductors) are much less bulky than their antenna counterparts. In applications that do not require high data rates, underground wireless networks based on MI technique have been demonstrated to be highly reliable [4].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Impact of Soil Conductivity on Underground Magneto-Inductive Channel

Zhang

Huang

et al. 2015

This letter presents our experimental endeavor to characterize underground magneto-inductive channels. Specifically, a range of experiments are conducted in realistic underground environments, and the measurement data are compared with channel models established in prior publications. The channel model proposed in [1], which incorporates the impact of soil conductivity, is found in better agreement with the measurement data than models without soil conductivity included. It is therefore concluded that, soil conductivity plays significant roles in underground magneto-inductive channels and must be modeled accurately. 1536-1225 (c) Index Terms-Experimental characterization, magneto induction, underground, wireless channel model

“…Also, our attenuation calculation showed that EM wave propagation is sensitive to change in conductivity of soil, thereby lowering signal to noise ratio. The current TTE communication systems use the EM wave as a signal carrier source [3][4][5].…”

Section: Electromagnetic Wave Transmissionmentioning

confidence: 99%

“…Such a low frequency has small EM attenuation in the soil medium compared to MHz frequencies. It was reported that the 4 kHz TeleMag system was successfully demonstrated for two-way voice communication between surface and underground using a 60-foot (20 m) loop antenna [3][4][5]. However, the large size of the loop antenna is undesired for the limited space of mine underground.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Pulsed Ferrite Magnetic Field Generator for Through-the-earth Communication Systems for Disaster Situation in Mines

Bae¹,

Hong²,

Lee³

et al. 2013

Journal of Magnetics

A pulsed ferrite magnetic field generator (FMFG) was designed for the use in the 1000 m long through-theearth (TTE) communication system for mining disaster situations. To miniaturize the TTE system, a ferrite core having 10,000 of permeability was used for the FMFG. Attenuation of the magnetic field intensity from the FMFG (200-turn and 0.18 m diameter) was calculated to be 89.95 dB at 1000 m depth soil having 0.1 S/m of conductivity. This attenuation was lower than 151.13 dB attenuation of 1 kHz electromagnetic wave at the same conditions. Therefore, the magnetic-field was found to be desirable as a signal carrier source for TTE communications as compared to the electromagnetic wave. The designed FMFG generates the magnetic field intensity of 1 × 10 −10 Tesla at 1000 m depth. This magnetic field is detectable by compact magnetic sensors such as flux gate or magnetic tunneling junction sensor. Therefore, the miniature FMFG TTE communication system can replace the conventional electromagnetic wave carrier type TTE system and allow reliable signal transmission between rescuer and trapped miners.