Transfer of vertical geodetic control using only one GPS receiver: a case study

Normally, the precise transfer of vertical geodetic control by GPS requires two receivers operating simultaneously in carrier-phase mode. This paper describes the transfer of vertical control into areas that have sparse existing geodetic control using only a single GPS receiver. The GPS data were processed using the Australian Surveying and Land Information Group’s (AUSLIG’s) AUSPOS on-line GPS processing facility (www.auslig.gov.aulgeodesylsgc/wwwgps/wwwgps.htm). These GPS-estimated ellipsoidal heights were transformed to the Australian Height Datum (AHD) using AUSGeoid98. In the case study area of Western Australia, a small bias had to be applied to account for the absolute difference between AUSGeoid98 and the AHD before the detailed spirit-levelling traverses, tied to these single-GPS-derived heights, were integrated with a digital elevation model.