CRITICAL ERROR EFFECTS AND ANALYSIS IN CARRIER PHASE-BASED AIRBORNE GPS POSITIONING OVER LARGE AREAS

For high accuracy airborne differential GPS positioning over large areas, i.e. a monitor-remote separation over 50 km, residual errors from the atmosphere and orbit, as well as multipath effects are the main error sources which limit the potential positioning accuracy. The effects of these critical errors are quantified and analyzed using test data collected during an airborne positioning campaign. Four Trimble 4000 SSE receivers were used, with two serving as monitors and the other two as remote receivers installed in the aircraft. Monitor-aircraft separations of up to 200 lan were experienced during the test. A formula is derived for analytical estimation of orbital error effects. Results and discussions relevant to the critical error analysis are presented with emphasis on their effects on the positioning results.