Research On Multi-frequency And Multi-mode Model For Precise Point Positioning

With the continual improvement of the modernization of the GPS and GLONASS and with the development of the COMPASS and GALILEO in GNSS system,accompanied by the improvement of IGS precise ephemeris and clock product,the year of tri-frequency(even quadri-frequency)navigation and positioning has come.Single(double)frequency precise point positioning(PPP)technology based on GPS or GLONASS and their combination trend to develop in the direction of multi-frequency multimode and higher precision.Lots of researches on PPP have been done at home and abroad,and considerable achievements about dual-frequency model and algorithm,wild value rejection and cycle slip detection and repairing,and pointing precision have been obtained.But it still cannot be perfectly solved that the problems of ambiguity fixing and rapid convergence,and the composite pattern weight and high order terms ionospheric effects elimination,etc.Especially when it comes to expanse and improve the multi-frequency multimode under the premise of the positioning theory and the model algorithm.In order to solve these problems,systematic researches are done in this paper,and come to the conclusion that:1.Some researches on the progress of GNSS system,key technologies of PPP,IGS precise ephemeris and clock product are done,then emphasize on resolving the feasibility of multi-frequency multimode,raise the frequency mode,and put forward the thought of multi-frequency multimode PPP.2.Do some researches on the references of PPP and error correction model in GNSS system,solve the problem spatial reference between the unified transformation parameters set,time reference and error correction.Unified formulas are deduced from GNSS time system,and give their mutual conversion,and divide the errors into traditional error and peculiar error two categories,then develop a quantitative analysis software.3.Via the multi-frequency observation data combination theory,data processing and parameter estimation direction for research,focused on solving the problem of multi frequency combination coefficients selection criteria,PPP data preprocessing and parameter estimation problem.The theory of hypothesis testing is used for cycle slipdetection and repairing,the TurboEdit method which based on the M-W,IF and GF linear combinations are used for dual frequency data preprocessing,established a tri-frequency cycle-slip detection and repair theory,at the same time according to the different positioning model of choosing different parameters estimation method.4.Deduce the code-quasi phase combination of single frequency PPP model,based on the study of the PPP theory and model algorithm.Put forward the phase deviation estimation of the tri-frequency mixed code-phase combination and the quadri-frequency inter-satellite single difference PPP model.Then the model of multi-frequency multimode PPP modeling is given.5.Use the IGS station data for the PPP experiments of single frequency,dual frequency,dual frequency dual mode and multi-frequency.Verify the static and dynamic model,and do the precision alignment to confirm if the theory,algorithm and model is accurate and reliable.