Mining Publication: Surface Magnetic Field Noise Measurements at Geneva Mine
Original creation date: September 1974
Measurements of surface magnetic field noise were made at various locations over the Geneva Coal Mine near Price, Utah, on June 12, 1973. The locations selected were on the surface over emergency locator beacons underground at depths between 350 meters (1150 ft.) and 488 meters (1600 ft.). The surface terrain where these measurements were made was mountainous, and access was difficult. There were no power lines within several miles, and the weather was clear; therefore, the magnetic noise levels were about as low as will normally occur. Results of measurements of distant sferics indicate rather sharp cutoff frequencies below which broadband, impulsive noise is attenuated. The mechanism of propagation for this noise above the daytime cutoff frequency of 3500 Hz and the nighttime cutoff frequency of 1700 Hz is deduced to be a waveguide formed by the D or E layers of ionosphere as an upper plane and the earth as a lower plane. The measurement systems used are similar to those used earlier. The technique is to record broadband, analog signals, digitize the data, and use a fast-Fourier transform to obtain spectral plots. This technique is novel in that it can measure simultaneously all magnetic field energy within a limited portion of the spectrum for a limited time, and, after processing, reproduce the events occurring in that time interval in great detail.
Authors: JW Adams, WD Bensema, NC Tomoeda
Contract/MOA Report - September 1974
NIOSHTIC2 Number: 10001388
National Bureau of Standards. U.S. Bureau of Mines contract No. H0133005. NBSIR 74-369. NTIS No. Com/741-1688, 1974; :1-40
See Also
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- Electromagnetic Noise in Grace Mine
- Electromagnetic Noise in Itmann Mine
- Electromagnetic Noise in Lucky Friday Mine
- Electromagnetic Noise in McElroy Mine
- Electromagnetic Noise in Robena No. 4 Coal Mine
- Measuring the Methane Content of Bituminous Coalbeds
- Medium-Frequency Propagation in Coal Mines
- Methane-Air Mixtures Ignited by CW Laser-Heated Targets on Optical Fiber Tips: Comparison of Targets, Optical Fibers, and Ignition Delays
- Modeling and Data Analysis of 50 to 5000 kHz Radio Wave Propagation in Coal Mines
- Noise Source Identification on a Horizontal Vibrating Screen
- Passive Fiber Optic System for Locating, Tracking, and Communicating with Personnel in Coal Mines
- Preliminary Performance Predictions For Electromagnetic Through-The-Earth Mine Communications: A Collection of Working Memoranda
- A Spatial/Spectral Domain Microwave Coal Seam Imaging Sensor-Progress in Signal Processing
- Three Dimensional Microseismic Monitoring of a Utah Longwall
- Time and Amplitude Statistics for Electromagnetic Noise in Mines
- Page last reviewed: 9/21/2012
- Page last updated: 9/21/2012
- Content source: National Institute for Occupational Safety and Health, Mining Program