Using GPS carrier phase in real time kinematic positioning

In this paper, two different techniques of the Global Positioning System (GPS) are investigated to proceed the real time kinematic positioning. The first method is the carrier smoothed code (CSC) technique, in which the pseudoranges and the carrier phase observables are combined to acquire more accurate ranging measurements. In the second method, pseudorange observables are applied for initial position estimation, and carrier phase measurements are used for positioning updates. The ambiguity search (AS) technique is adopted to resolve the carrier phase's integer ambiguity problem. To verify the above algorithms, both static and kinematic experiments were conducted. In the static experiment, two Magnavox 4200 GPS receivers were located on both ends of a fixed baseline 1.21 meters in length. Compared with the steady state triple-difference solutions, the baseline length errors of the CSC and AS techniques were abouts 0.5 meters (1 sigma) and 0.2 meters (lo), respectively. An unmanned boat directed to go through six pre-specified way points was used in the kinematic experiment. Two Motorola Oncore GPS receivers were installed on the boat and the on-site reference station, respectively, for relative positioning. The boat trajectories computed by the different methods are shown in the experimental results.