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Adaptive - Noise - Cancellation Techniques for Through-the-earth Electromagnetics. Volume II.

Authors
Raab-FH
Source
NTIS: PB/85-111409 Available for Reference At Bureau Libraries :121 pages
Link
NIOSHTIC No.
10004200
Abstract
An electromagnetic (em) system to locate trapped miners at coal mine depths was investigated. The use of such a system in deep mines 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 efective noise level by combining several received signals that contain correlated noise. The signals can be obtained from either a remote magnetic antenna or a local electric antenna. This report presents the results of a simulation of the use of anc techniques in a through-the-earth em system. A multicomponent elf noise model that incorporates impulsivity, direction of arrival, and ground characteristics was developed. Nonlinear processors (nlp) for elf noise were compared and the adaptive clipper was found to be preferable. Direct-matrix- inversion (dmi) and least-mean-square anc techniques were compared and the dmi algorithm was preferable. The performance of the combined nlp-anc system was evaluated.
Publication Date
19830101
Document Type
CP; Final Contract Report;
Fiscal Year
1983
NTIS Accession No.
PB85-111409
NTIS Price
A07
Identifying No.
OFR 189-84
NIOSH Division
PRC;
Source Name
NTIS: PB/85-111409. Available for Reference At Bureau Libraries.
Performing Organization
Green Mountain Radio Res.
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