Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

GPS positioning is suggested as the way which quickly provide the accurate positions in geophysical surveys. Since the digital topographic maps over the whole country have been almost made up, in geophysical surveys, the combined use of GPS positioning and digital topographic map would customize the time and cost of field survey and data interpretation. Among various differential GPS methods for increasing precision of positioning, we recommend RDGPS (realtime differential GPS) in the viewpoint of convenience of field work as well as accuracy. There are some geophysical instruments which have the capability of interfacing with GPS either direct or indirect way. Direct interface can be used for those instruments which receive the GPS positioning data in the NMEA-0183 format through RS-232C cable and record them together with geophysical data. Magnetic survey instrument such as G-858 and non-electric contact resistivity survey instrument such as OhmMapper are of this kind. When direct interface is impossible, there is another way to interface with GPS so called indirect interface. In order to use indirect interface, the geophyscial instruments have to be synchronized to GPS time precedently and then accurate positions could be acquired through post-processing. GPR survey instrument such as Ramac/GPR and electromagnetic survey instrument GEM 300 are of this kind. When performing integrated geophysical surveys to the same area, one of the most important things is to locate the individual survey results to the correct positions for the analysis of correlations of each geophysical data. In this case, the most convenient way to obtain correct positions is to use the GPS positioning.