Rapid Ambiguity Resolution Algorithm for Multi-constellation Between Reference Stations Based on Ambiguity Tight Constraint

Abstract

The development of multi-GNSS remarkably increased the number of available satellites, but how to solve the multi-dimensional ambiguity parameters quickly and accurately in network RTK technology is still an issue full of perplexity and significance. To ensure the virtual station have more available satellites under the occlusion environment, a fast ambiguity resolution method for base station based on ambiguity tight constraint was proposed in this paper. Firstly, the optimal subset of ambiguity is selected by partial ambiguity resolution (PAR) strategy, and then impose strong constraints on the ambiguities of these satellites. Finally, update the filter equation and assist in fixing the ambiguity of other satellites. The real measured baseline data which contain GPS, BDS and GLONASS from Tianjin CORS and Curtin University was used in the experiments, and the results illustrated that this method could significantly shorten the initialization time of ambiguity between base stations, accelerate the convergence speed of newly-arisen satellites, and increase the number of available satellites of RTK virtual observations (especially low-elevation angle satellites), that providing a reliable guarantee for high-precision positioning in the occlusion environment, such as the roads in cities.