AbstractBeiDou Navigation Satellite System (BDS) is a full global positioning system with multiple satellites in three different orbits. It is also equipped with the modernised frequency signals that are compatible and interoperable with other satellite systems. With these merits, BDS can now be used in positioning, navigation, and timing independent of other satellite constellations. Currently, the precise point positioning (PPP) technique has become a versatile tool for computing the receiver position. However, the inter-system biases (ISB) and hardware biases are a major concern in combined Global Navigation Satellite System (GNSS) and multi-frequency data processing. To improve data processing, this thesis aims at developing a novel multi-frequency BDS PPP algorithm.
To enhance the multi-BDS constellation, this thesis reparameterises the PPP functional model in terms of ISB and multi-GNSS precise products using two different generations of BDS satellites. The results establish an improvement in position, convergence, and pseudorange residuals. This thesis also proposes a hardware bias handling scheme based on the BDS multi-frequency signals. This is achieved by extending the traditional triple-frequency PPP model to a quad-PPP model. The experimental tests are conducted to test the validity of the proposed model, and the results reveal that the suggested model generally outperforms the traditional one in terms of the quality of the estimated position and biases. Furthermore, this work also puts forward an extended mathematical model for addressing biases emanating from BDS satellite orientation. The model deploys the satellite attitude quaternions in the modelling of BDS satellite attitude, and is validated using the standard attitude. As part of model testing, the thesis undertakes kinematic and static PPP experiments. The results uncover that the technique can upgrade positioning solutions in both modes. In addition, the approach is also capable of lowering the estimated phase residuals.
Keywords: PPP, ISB, hardware biases, satellite attitude, residuals
|Date of Award
|15 Mar 2024
|Yung-Tsang Chen (Supervisor) & C.F. Kwong (Supervisor)
- hardware biases
- satellite attitude