Interaction of radio transmissions on mine monitoring and control systems

"This report describes the creation of an efficient method to determine if command, control, communication, and monitoring (3cm) equipment in coal, metal, and nonmetal mines is susceptible to radio frequency interference (RFI) from the medium-frequency (MF) radio communications system. A qualitative and quantitative RFI test plan was developed for in-mine and laboratory evaluation of the equipment. The laboratory testing was accomplished using the transverse electromagnetic wave (TEM) test chamber. Detailed information on the test plan and the tem test chamber is included. During in-mine testing of the MF system, some underground equipment malfunctioned when the transmitter's radiating antenna was in close proximity. Electromagnetic compatibility (EMC) testing was done on three levels: component (circuit or box), subsystems, and system. Nine tables are included that show the results of testing various equipment for RFI." - NIOSHTIC-2NIOSHTIC no. 100055571986Contract JO12303

Through-the-earth electromagnetic trapped miner location systems : a review

"In its role of providing technical assistance to the mining industry, the Bureau of Mines' Tuscaloosa Research Center has conducted research to develop trapped miner location systems which would aid in locating miners trapped by underground mining disasters. Efforts to produce electromagnetic systems for the location of trapped miners underground and to communicate with them were surveyed, from the 1920's to 1981. Theoretical studies of through-the-earth electromagnetic transmissions are described as well as studies of the electrical characteristics of various rocks, minerals, and soil. Several trapped miner location systems are reviewed including the Westinghouse systems, the DEVELCO system, and an automated three-dimensional location system, and the phase difference of arrival technique. Tangential research, relevant to trapped miner location systems is described. A comprehensive bibliography covering all aspects of trapped miner, through-the-earth electromagnetic location and communications systems is appended." - NIOSHTIC-2NIOSHTIC no. 1000482

IEEE Antennas Propag Mag

An efficient procedure for modeling medium frequency (MF) communications in coal mines is introduced. In particular, a hybrid approach is formulated and demonstrated utilizing ideal transmission line equations to model MF propagation in combination with full-wave sections used for accurate simulation of local antenna-line coupling and other near-field effects. This work confirms that the hybrid method accurately models signal propagation from a source to a load for various system geometries and material compositions, while significantly reducing computation time. With such dramatic improvement to solution times, it becomes feasible to perform large-scale optimizations with the primary motivation of improving communications in coal mines both for daily operations and emergency response. Furthermore, it is demonstrated that the hybrid approach is suitable for modeling and optimizing large communication networks in coal mines that may otherwise be intractable to simulate using traditional full-wave techniques such as moment methods or finite-element analysis.YLH8/Intramural CDC HHS/United States2015-10-14T00:00:00Z26478686PMC460587

IEEE Trans Ind Appl

The underground-mining environment can affect radio-signal propagation in various ways. Understanding these effects is especially critical in evaluating communications systems used during normal mining operations and during mine emergencies. One of these types of communications systems relies on medium-frequency (MF) radio frequencies. This paper presents the simulation and measurement results of recent National Institute for Occupational Safety and Health (NIOSH) research aimed at investigating MF coupling between a transmission line (TL) and a loop antenna in an underground coal mine. Two different types of measurements were completed: 1) line-current distribution and 2) line-to-antenna coupling. Measurements were taken underground in an experimental coal mine and on a specially designed surface test area. The results of these tests are characterized by current along a TL and voltage induced in the loop from a line. This paper concludes with a discussion of issues for MF TLs. These include electromagnetic fields at the ends of the TL, connection of the ends of the TL, the effect of other conductors underground, and the proximity of coal or earth. These results could help operators by providing examples of these challenges that may be experienced underground and a method by which to measure voltage induced by a line.CC999999/Intramural CDC HHS/United States2016-10-24T00:00:00Z27784954PMC5076858vault:1986

Propagation of EM signals in underground mines.

"This report is a comprehensive summary of the results of the propagation measurements program conducted for the Bureau of Mines. Data were gathered in the medium frequency (mf) range from a cross sample of six mines representative of the industry having typical wireless requirements. From the data that were gathered, a logical method of data reduction is presented that culminates in a set of average attenuation characteristics for all mines visited. These characteristics define a typical mf wireless system when the communication range requirements are known. Direct through-the- earth propagation and the range enhancement mechanism due to coupling on-and-off conductors are evaluated and related to the planning of a typical wireless mf communications system." - NIOSHTIC-2NIOSHTIC no. 19770901H0036602

Analysis of factors affecting wireless communication systems in underground coal mines

Since recent disasters in the mining industry in 2006 the push for a reliable communication system has became a high priority. This thesis will discuss each wireless communication system available and/or being developed for underground mines as well as the frequencies that will be used for each system\u27s operation.;The second part of the investigation will be on the factors affecting these frequencies as well as possible ways to model these factors analytically. It is important to understand these factors in order to make intelligent conclusions as to what communication systems will perform adequately in an underground mining environment.;The third area discussed will be an analysis of empirical studies completed by various agencies, companies, and schools (including West Virginia University). These studies were completed to judge the practicality and performance of each system. Practicality is important to the mining industry. The industry tends not to accept new technology quickly, so proof of performance is a key component to introducing the products into the market

Prog Electromagn Res M Pier M

Magnetic proximity detection systems (PDSs) used in underground mines occasionally generate false alarms when the miner-wearable component (MWC) is close to nearby conductors such as power cables. This is because the signals from the generators (antennas) of the PDS wirelessly couple to nearby cables, travel along these cables, and then couple back from the cable to a distant MWC to cause a false alarm. In order to manage such a false alarm, it is necessary to understand the basic near-field coupling characteristics from a generator to a long wire. Researchers from the National Institute for Occupational Safety and Health (NIOSH) have developed a method to measure such coupling characteristics for a ferrite-cored antenna to a straight wire. The method is introduced in this paper along with the test results.CC999999/Intramural CDC HHS/United States2018-12-28T00:00:00Z30595794PMC6309894vault:3128

Underground Mining Monitoring and Communication Systems based on ZigBee and GIS

ZigBee as a wireless sensor network (WSN) was developed for underground mine monitoring and communication systems. The radio wave attenuations between ZigBee nodes were investigated to measure underground communication distances. Various sensor node arrangements of ZigBee topologies were evaluated. A system integration of a WSN-assisted GIS for underground mining monitoring and communication from a surface office was proposed. The controllable and uncontrollable parameters of underground environments were assessed to establish a reliable ZigBee network

Elastic wave measurement in rock engineering

Imperial Users onl