| Some GPS applications require precise single point positions that are stable over time. However, changes in GPS error sources can lead to a degradation in the relative (over time) stability of the estimated positions. In this research, the temporal characteristics of the orbital, satellite clock, and ionospheric errors are analyzed independently. Satellite clock and orbit errors are analyzed by comparing broadcast and precise satellite clock corrections and orbits. Dual frequency carrier phase data is used to assess the change in the ionospheric error. The remaining errors, which include the tropospheric error, multipath, and noise are investigated together. To compute the remaining errors, the receiver clock error must be removed, which is possible if the position is known. The analysis comprises primarily of assessing error behaviors and magnitudes through time and frequency analyses. In this way, the differences in variability of the errors are easily determined. (Abstract shortened by UMI.)... |
