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Vertical magnetic noise in the voice frequency band within and above coal mines.

Authors
Durkin-J
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8828, 1983 Dec; :1-27
NIOSHTIC No.
10003224
Abstract
Information on vertical magnetic noise in the voice frequency band, both within and above coal mines, is needed for the evaluation of through-the-earth baseband electromagnetic communications at mines where horizontal loop antennas are used. This report discusses the theory of the source of electromagnetic noise, the propagation of this noise to an observation point above a mine, and its interaction with the local earth conductivity structure, which gives rise to vertical magnetic noise. The relationship of surface noise to underground noise is also discussed. Bureau of Mines investigators made surface and underground vertical magnetic noise measurements at a number of coal mines located throughout the United States. These data were modeled through regression analysis to characterize expected noise levels. The results are presented, including results in one-third octaves for use in evaluating the expected performance of through-the-earth communication systems by articulation-index studies.
Keywords
Mining-industry; Electromagnetic-energy; Electromagnetic-fields; Electromagnetic-interference; Electromagnetic-radiation; Statistical-analysis; Underground-mining; Radio-waves; Coal-mining
Publication Date
19831201
Document Type
IH; Report of Investigations
Fiscal Year
1984
NTIS Accession No.
PB84-152123
NTIS Price
A03
Identifying No.
RI-8828
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8828
State
PA
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