Theoretical noise and propagation models for through-the-earth communication.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, :1-45
A survey of the literature on extremely low-frequency and very low- frequency atmospheric noise was made. Most measurements have concentrated on vertical electric field and the horizontal magnetic field rather than the vertical magnetic field, which is of interest in transmission between horizontal loops. The limited vertical magnetic field data indicate that the vertical component is generally 10 to 20 db below the horizontal component. Three laterally inhomogeneous earth models were analyzed for conversion of horizontal to vertical magnetic field. The rough surface model examines surface effects, the inhomogeneous thin sheet model treats volume effects, and the buried cylinder model treats localized manufactured effects. All three models predict the possibility of significant conversion from horizontal to vertical magnetic field. It was found that the predicted fields more nearly model the measured data than does the homogeneous half-space model.
Noise-exposure; Noise-frequencies; Noise-pollution; Noise-protection; Noise-transmission; Noise-waves; Electrical-fields; Electrical-measurement; Electrical-waves; Magnetic-fields; Magnetic-properties; Miners; Mining-industry
CP; Final Contract Report
NTIS Accession No.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines
National Telecommunications and Information Administration