Influence of the Cutoff Angle and the Bearing in High-Precision GPS Vector Determination

Accurate global positioning system (GPS) vector determination is now one of the major applications in modern geodesy. Most of the errors are modeled either to smooth atmospheric effects or to remove biases, such as clock offsets. The network design criteria and the vector processing solutions are based in distances to the reference stations and in the time span of the vectors involved in the sessions. Thus, the final solutions are computed accurately and the residuals show the quality of the computations. What is not usually taken into account in the final vector computation is the bearing of the vector to be processed, as the cutoff angle is considered fixed. This note deals with the variation on the final solution due to different cutoff angles, and still more importantly to the bearing of the vector in high- precision GPS vector determination. If in the future, the International Global Navigation Satellite System Service starts to distribute orbits that are created using the ANTEX file, this elevation-angle dependency should diminish.