BDS Aided GPS Ambiguity Fixed Precise Point Positioning Based On Integer Phase Clock Method

Precise Point Positioning (PPP) integrates the advantage of standard single point positioning and relative positioning, and it’s a technological revolution of GNSS positioning technology after RTK/Network RTK technology. Since 1997, PPP has been developing rapidly in theory, and widely used in many engineering fields. However, most of the mature and applicable PPP services are based on float solution, limiting its future development and application. With the continuous development of BDS, multi-system positioning will become the main way of future positioning. Thus BDS Aided GPS ambiguity fixed PPP based on integer phase clock method needs to be researched insurgently.The thesis systematically introduces the observation model of PPP, position error correction models, quality control methods and pararmeter estimation method. The thesis analyzed the reason that un-difference ambiguity cannot be fixed to integers, and then used integer phase clock method for integer ambiguity resolution with the designed ambiguity fixing process. Based on the above theory, SEU-PrecisePos software was written which used the partial ambiguity research method. The software and the observation data were used to conduct extensive test to analyze the BDS impact on ambiguity fixed PPP.The main work and conclusions are as follows:(1) The Basic Principles of Precise Point Positioning and Parameters Estimation MethodMain observation models of PPP were clarified in detail, and the single difference between satellites ionosphere-free model was determined as the experimental model. This thesis also introduced the models of each positioning error sources and the methods of data quality control in detail. In order to satisfy the requirement of PPP calculation, we use robust Kalman filtering instead of standard Kalman filtering.(2) GPS/BDS Ambiguity Fixed PPP Based on Integer Phase Clock Method Analyzed the reasons that ambiguity cannot be fixed to integer in traditional PPP model, we chose integer phase clock method for integer ambiguity resolution and designed ambiguity fixing process.Based on the integer phase clock method, proposed ambiguity fixing process which take into account quality control. For PPP solution we used partial ambiguity research metod which improved on Least-square Ambiguity Decorrelation Adjustment method. Experiments show that using partial ambiguity search method, the time to first fixed solution is shorten by 10.13%.(3)GPS/BDS Ambiguityu Fixed PPP Experimental of Verification Using Visual Studio 2010, SEU-PrecisePos software was written to achieve the above algorithm. Numerous PPP experimental was carried out on SEU-PrecisePos software. The result shows that compared with float solution, the ambiguity fixed solution shorten the convergence time by 13.92%; positioning accuracy upgrade by 29.79%; positioning error rms reduce by 24.20%. Compared with GPS fixed solution,the GPS/BDS fixed solution shorten the time to first fixed solution by 7.95%; positioning accuracy of east direction upgrade by 15.57% and total positioning accuracy upgrade by 4.80%; positioning rms reduced by 15.38%.