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Abstract
As GLONASS has gradually been developed towards its full constellation, it becomes clear that GLONASS will bring significant benefits to worldwide geodetic applications of global satellite navigation systems. With the recent revitalization of GLONASS, GPS/GLONASS receivers have been equipped at most International GNSS Service (IGS) tracking stations and regional CORS networks worldwide. Precise IGS orbits for GLONASS, consistent GPS/GLONASS CODE orbits as well as combined GPS/GLONASS observations are available for users. So it becomes worthwhile to investigate the advantages of the combined GPS/GLONASS solutions for precise surveying and geodetic applications.
This research focuses on analysing combined GPS/GLONASS observations for long baselines and short baselines. Both mathematical model and stochastic model have been discussed based on the results from the observations obtained from IGS stations and testing observations for rapid static baselines. This thesis has focused on the following major aspects:
a) Modelling for combined GPS/GLONASS data processing. The possible mathematical models have been discussed and verified with numerical results. For stochastic modelling, the elevation-based model, SNR-based model and a real-time stochastic model have been analysed.
b) GPS/GLONASS data processing for long baselines. GPS and GPS/GLONASS long baselines from two networks have been analysed, aiming to assess the influence of adding GLONASS data to the GPS-only long baseline solutions. The IGS final GPS precise orbits and fully consistent GPS/GLONASS orbits from CODE have been utilised in all these baseline solutions. GPS-only and GPS/GLONASS observations have been processed respectively, using the same processing strategy. The results of the GPS-only baselines and GPS/GLONASS baselines have been compared. It has been demonstrated that the accuracy for long baselines cannot be improved significantly by introducing GLONASS observations.
c) GPS/GLONASS data processing for rapid static baselines. Observations from rapid static baseline have been processed using Leica Geo Office, and the results from GPS-only baselines and combined GPS/GLONASS baselines have been analysed. From the results, it can be seen that the accuracy have been improved by integrating GPS/GLONASS for rapid static baselines in built-up areas.