Research On GNSS-based Location Determination Of High Earth Orbit Satellites

With the continuous development of space technology, GNSS receiver develops from ground receiver to spaceborne receiver, and the demand for highly elliptical earth orbit receiver is growing. Due to the velocity of spacecraft or satellite is high, it brings the Doppler shift. Besides, signal acquisition and tracking is difficult. We must improve the sensitivity of spaceborne GNSS receiver, so the design of spaceborne receiver will be more difficult. In addition, the ionospheric error is the main error source which affects the accuracy of location seriously, we need an effective way to reduce ionospheric error to eliminate the impact of the ionosphere on location results.(1) Providing basic principles and system components of spaceborne GNSS receiver, and analyzing the GNSS receiver’s signal acquisition, tracking, and navigation data analysis method, and extracting the exact satellite launch time.(2) Building constellation models, simulation of high orbit receiver’s number of visible satellites at different sensitivities and different combinations of satellite navigation systems. We studied the spaceborne receiver’s satellite visibility of GEO orbit and HEEO orbit.(3) Studying the GDOP of different combinations of satellite navigation systems, and analyzing the relationship between the GDOP and the number of visible satellites and location accuracy. GDOP is related to satellite elevation angle, we proposed satellite selection algorithm based on satellite elevation, the result of experiments shows that the algorithm improves location accuracy.(4) Analyzing the error sources which cause the location error, the ionospheric error is the main error. Studying ionospheric error correction method. We research single-frequency ionospheric correction, dual-frequency ionospheric correction and tripe-frequency ionospheric correction, and calculating the corresponding observation noise. Measuring the relationship between ionospheric correction effect and observation noise, and selecting the best method for ionospheric correction of different systems.Methods of improving the location accuracy of GNSS receiver are researched in this thesis, which include different combinations of satellite navigation systems, effective satellite selection algorithm and ionospheric error correction. We demonstrate the effectiveness and feasibility of these methods with experimental results, which provide methods of the development of GNSS receiver.