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Mining Publication: Adaptive-Noise-Cancellation Techniques for Through-the-Earth Electromagnetics: Volume III
Keywords: Communications, location tracking, and signalling Noise cancellation Through-the-earth communications systems
This page is archived for historical purposes and is no longer being maintained or updated. Contact NIOSH Mining if you need an accessible version.
Original creation date: February 1984
Authors: FH Raab
Contract/MOA Report - February 1984
Download PDF Document (3.06 MB)
Green Mountain Radio Research Company. U.S. Department of the Interior, Bureau of Mines. Contract No. J0318070, Feb. 1984; 100 pp
An electromagnetic (EM) system for the location of trapped mine workers at coal-mine (300 m) depths has been developed. The use of such a system in deep mines (1-km depth) requires transmission at extremely low frequencies (ELF) and a reduction in the effective noise level beyond that which can be obtained by acceptable integration times. Automatic-noise-cancellation (ANC) techniques reduce the effective noise level by combining several received signals that contain correlated noise. Such signals can be obtained either from a remote magnetic antenna or a local electric antenna. During Phase III of this program, real ELF noise data were acquired and used to test the ANC algorithms developed during Phase II. The ELF noise data were obtained from analog recordings made by Develco under another Bureau of Mines contract. Digitization was accomplished by an A/D converter that was added to a GMRR computer. Phase III tasks included preparation of software for digitization, computer-computer communication, data processing, and statistical analysis. Useable data were obtained from eleven half-hour tapes containing noise from one axis of the primary antenna and three axes of the remote antenna. The overall average improvement in SNR was 4.1 dB. However, the average improvements for the individual X, Y, and Z axes were 4.2, 11.9, and -1.9 dB, which roughly follow the observed noise power. Nonlinear processing was not effective with this noise.
Image of publication Adaptive-Noise-Cancellation Techniques for Through-the-Earth Electromagnetics: Volume IIIContract/MOA Report - February 1984
Download PDF Document (3.06 MB)
Green Mountain Radio Research Company. U.S. Department of the Interior, Bureau of Mines. Contract No. J0318070, Feb. 1984; 100 pp
See Also
Apparent Earth Conductivity Over Coal Mines as Estimated from Through-the-Earth Electromagnetic Transmission Tests
Low-Frequency Electromagnetic Noise Cancelling Antenna System
Performance Evaluation of Electromagnetic Techniques for the Location of Trapped Miners
Preliminary Performance Predictions For Electromagnetic Through-The-Earth Mine Communications: A Collection of Working Memoranda
Propagation of EM Signals in Underground Mines
Theoretical Noise and Propagation Models for Through-the-earth Communication
Through-The-Earth Wireless Real-Time Two-Way Voice Communications
Two-Way, Through-the-Earth Emergency Communication System for Trapped Miners and the Surface
Ultra-Low Frequency Through-the-Earth Communication Technology
Vertical Magnetic Noise in the Voice Frequency Band Within and Above Coal Mines
Page last reviewed: September 21, 2012
Page last updated: September 21, 2012
Content source: National Institute for Occupational Safety and Health, Mining Program
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