Study On Data Processing Algorithms Of BeiDou Precise Positioning With Multi-frequency Observations

In the process of advancing the modernization of the navigation system,future global navigation satellite systems such as GPS,GLONASS,Galileo and BDS began to provide multi-frequency signal service which may bring great advantages to GNSS precise positioning applications.This dissertation lays emphasis on the study of the theory of multi-frequency combination observations,cycle-slip detection and repair,and ambiguity resolution with multi-frequency observations.The main research as follows:1.The mathematical model of BDS triple-frequency carrier-phase linear combination is given,and the wavelength,ionospheric error and the observation noise of linear combination are systematically analyzed;Also having used the integer linear transformation method as a basis,the optimization of the combination coefficient was realized by Matlab.By applying different combination coefficients to the cycle-slip detection,it was found that the results of combined cycle slip can be detected with the sum of the combination coefficients is none zero is more than 0.5 cycles;By applying different combination coefficients to the ambiguity resolution for triple-frequency observations,it was found that the residual value of ambiguity obtained by the combination of non-zero coefficients but long wavelengths are about 0.6 cycles,the correct ambiguity fixed solution can be obtained by the appropriate ambiguity search method,this kind of coefficients can be used in short baseline ambiguity resolution.2.The cycle-slip detection method of triple-frequency pseudo range/phase and the method of geometric-free phase are studied.From the purpose of improving the success rate of cycle-slip detection,the optimal combination coefficients of pseudo range/phase is selected based on the principle of minimum standard deviation of cycle-slip,the disadvantage that the geometry-free carrier combination can't detect some special cycle-slip has been analyzed.Finally,we use real data to detect and repair cycle-slip based on the optimal combination coefficients.The results show that two methods can accurately detect and repair different combinations of cycle-slips.3.The basic principle of ambiguity resolution method of GF-CIR is studied,then the error of each step of the GF-CIR method is analyzed,and the solution results of the GF-CIR method at different baseline lengths are analyzed by an example.The experimental results show that GF-CIR method can solve the ultra-widelane and wide-lane combination ambiguity;But can't reliably solve the narrow-lane combination ambiguity because of the ionospheric delay effect.4.The algorithm of the ionospheric correction method and the ionophere-free combination method is presented in this paper.The experimental results show that two methods weaken the effect of ionospheric delay to some extent.However,the two methods amplify observation noise error,having certain limitations.