DOI: 10.5593/sgem2017/22/S09.057


A. Rusu-Casandra
Wednesday 13 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-02-7 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 22, 451-460 pp, DOI: 10.5593/sgem2017/22/S09.057


Establishing absolute geographical location in underground spaces such as mining exploitations, caves, deep crevasses, or in deep open pits is a technically difficult problem. Modern techniques used for general outdoor environments cannot be used in subterranean environments. The performant Global Navigation Satellite Systems (GNSS), such as GPS, GLONASS, GALILEO, BEIDOU are not available in underground spaces, due to the impossibility of propagation through soil and rock of radio waves at frequencies and transmitted power levels used by such positioning and navigation systems.
The paper points to another positioning and navigation system operating by radio waves, in use for more than 60 years in several technological generations, is the LORAN system, which uses long wave frequencies in the 90 – 110 kHz range, but this has experienced a decline in use and maintenance since year 2000, when satellite systems such as GPS took over as main radio navigation tool. Although is less complex and performant than GNSS, LORAN has recently been revived as a potential back-up and supplement for GNSS, and is being modernized in the form of eLORAN.
The paper aims to prove that technical characteristics of eLORAN allow it use for positioning in some underground spaces or areas where GNSS reception is impossible. Analysis of radio wave characteristics, especially the H-field component and its propagation, demonstrated the suitability of eLORAN signals to penetrate soil and rock layers to considerable depths. Comparative research also showed that accuracy of localization and timing synchronization offered by eLORAN is satisfactory for certain applications.

Keywords: positioning, timing, underground mapping, Loran-C, eLoran, H-field