Absolute kinematic GPS positioning for remote area

Method and the results of investigations to determine the position vector of a static or moving vehicle using the Global Positioning System (GPS) in the absolute (point) positioning mode is presented. The motivation of this research is to determine the position using GPS in remote area such as polar region and open sea in which it is difficult/impossible to set up a reference station. Starting from the basic positioning scheme with code observation, the most accurate positioning strategy using the phase is described. The achievable accuracy under no SA for each GPS data processing method is also assigned. The main strategy for the highest accuracy absolute positioning is to estimate GPS satellite clock errors independently, thus obviating the between-station differencing. The GPS clock errors are estimated at 30-second intervals using International GPS Service (IGS) orbits and stations. The clock error estimates are then used in an absolute positioning algorithm to determine the coordinates without any other reference site, which is the case for remote area surveys. Static and kinematic GPS data at 1-second sampling rate were processed and compared with the known values and the corresponding DGPS solutions. For the static case, an IGS station was assumed as unknown and its coordinates were estimated. For the kinematic case, the data from an aircraft survey near polar area were tested. The positions were compared with the corresponding DGPS solutions for each case. Since Selective Availability (SA) is currently turned off, its effect on the clock estimation as well as on the position is compared and emphasized.