Integrated method for instantaneous ambiguity resolution using new generation GPS receivers

Abstract

New generation GPS receivers, such as the Ashtech Z12, the Leica System 300 and the Trimble 4000SSi, output precise pseudorange and full wavelength carrier phase observations on both frequencies, even with A/S on. Hence all three general classes of ambiguity resolution techniques can be used: 1) search techniques in the measurement domain; 2) search techniques in the coordinate domain; and 3) search techniques in the estimated ambiguity domain. In this paper an integrated procedure, that combines all three ambiguity resolution techniques, is suggested for instantaneous ambiguity resolution for short baseline applications (typically less than 15 km), using the output of new generation GPS receivers. Experiments have been carried out using Ashtech Z12 and Leica System 300 receivers in static and kinematic positioning modes. Several different cases, with baseline lengths ranging from a hundred metres to 11.3 kilometres were tested. The rate of success of instantaneous ambiguity resolution using the suggested integrated method was better than 96.5%. The computation time for each epoch was less than 0.1 seconds.