Accuracy of Global Positioning System Broadcast Orbits for Relative Surveys

摘要

The accuracy of the Global Positioning System (GPS) broadcast orbits is important to the GPS community for both military and civilian applications. Surveyors, for example, would like to know if field processing of GPS baselines can be considered final. There is widespread belief that for accurate surveys (e.g., 1 ppm), post-processing with precise ephemerides is required. Precise versus broadcast comparisons are given in terms of along-track, cross-track, and radial plots and statistics based on hundreds of actual broadcast orbit comparisons. The proper use of the broadcast orbits is discussed. A strong measure of orbital accuracy is the effect of orbit errors on baseline vector computations. Numerous baseline vector solutions, using both precise orbits and broadcast orbits, are given.