Researches On Theory And Methodology Of Precise Orbit Determination Of Navigation Satellites

Global Navigation Satellite System(GNSS) were developed rapidly in recent decades. Its applications are very broad. In the high precise application field, it is demanded that the GNSS can provide high precise satellite orbits and clock offsets. In real time application field, getting real time and high precise satellite orbit and clock offset is the base of Precise Point Positioning and so on. This thesis researched the theory and technique of post-process and real time precise navigation satellite orbit determination and clock error estimation thoroughly using non-difference observations of GNSS. This effort has theoretical and practical significance. The main research contents and innovations are as follows:1. In accordance with the characters of navigation satellite, the main force models that affect the satellite orbit are provided. The solar radiation pressure model is focused on and the numerical integration methods are introduced. Using the post-processed results of GPS and GLONASS and BDS satellite precise orbit determination, their orbits are fitted and the acceleration and velocity and position series are analyzed. For the different orbit altitude of the three navigation satellite system, the acceleration results that are computed with different force models follow the ordinary rules. At the same time, the force models and numerical integration methods are proved to be high precision.2. The precision correction models of non-difference observations of GNSS are studied. Some useable code and carrier phase linear combinations of dual frequency observations and the partial derivatives that are needed when getting the linearized observation equations are provided. The behaviors of three type stochastic parameters which are kinematic station coordinates and receiver clock error and tropospheric zenith path delay are discussed. We write some programs to verify the high precise corrections model by processing real data. Coping with two type process noise such as random walk and white noise, the Kalman filter and sequential least square adjustment are used separately to process observations. The results of the two estimation methods are compared. These experiments show that the programs are correct and precise. So we build a platform to continue developping GNSS related problem.3. The orbit determination principle of batch processing algorithm of the least square adjustment is provided. The cycle slip editing methods for pre-processing GNSS observations are analyzed. The TurboEdit algorithm is discussed. Under the conditions of using ground tracking net, the ambiguities resolution algorithm of non-difference GNSS observations are discussed. The Gram-Schmidt orthogonal transformation method of obtaining independent baseline and independent double-difference ambiguity sets are proposed. The difference of three ways selecting independent double-difference ambiguity sets is discussed. The parameter elimination and recovery method are discussed. The behavior of two ways to handle inter-system bias for multimode receivers is analyzed when determinating orbit by processing combined multi-GNSS observations. By analyzing the satellite position and clock offset results of multi-GNSS combined precise orbit determination, the problem with uniforming the spacial and temporal datum is proposed.4. Using data from global and local track networks, we implement some experiments including global and regional high precise orbit determination and combined multi-GNSS orbit determination. Using global network data, the orbit determination results of GPS navigation satellites after ambiguities resolution can be improved from 0.039 m to 0.012 m which improve 70 percent in the average 1D position RMS compared with the IGS final precision orbit. For regional network, the success rate of ambiguity resolution is higher than global network. The regional orbit determination results from long arc session of three days after ambiguities resolution can be improved from 0.225 m to 0.095 m which improve 58 percent in the average 1D position RMS compared with the IGS final precision orbit. The combined multi-GNSS results show that the precision of GLONASS navigation satellite orbit can be improved obviously. The four orbit arcs results shows that the average 1D position RMS improve from 0.08 m to 0.07 m which improve 13 percent. Through precise point positioning experiment, it is validated that using uniform spacial and temporal satellite products can eliminate inter-system bias parameter when processing multi-GNSS data. So the different GNSS can be considered as one system by the user.5. In the light of the characters of BDS muti-frequency, we analyze linear combination observations being of benefit to detecting cycle slips. After studying the two algorithms of multi-frequency ambiguity resolution in detail, which are smooth residual ionosphere method and a new method for medium and long rage three frequency GNSS rapid ambiguity resolution, we present a new BDS multi-frequency ambiguity resolution method which integrate the above two methods. The ways to check BDS observation data quality are provided. The reduced-dynamic orbit determination method by using pseudo-stochastic pulse parameter is proposed. Aiming at BDS navigation application under the bad geometrical configuration, the three-satellite positioning principle is proposed. The ill-conditions problem under bad geometrical structure is analyzed. Using real BDS observations, the dynamic and reduced-dynamic orbit determination methods are tested. The results are analyzed. Using multi-GNSS observations, the combined BDS and GPS orbit determination are handled. The results show that for all type satellites such as GEO, IGSO and MEO, the radial component accuracy are improved. The BDS navigations satellites’ radial accuracy of overlap arcs can reach cm level when determinating orbit by using global 32 multi-GNSS stations observations.6. The real time navigation satellite clock offset determination problem is analyzed. The real time clock offset determination methods which are undifferenced method and epoch-differenced approach and an integrated method are discussed. The square-root information filter algorithm principle is discussed in detail. Using real data, the aspect of dicontinuty results at the edge of predicted orbit arc in global and regional cases is pointed out. The realtime undifferenced clock error determination process is simulated by using real observations. The precise point positioning by utilizing real time orbit and clock offset results is validated.