Research On Least Squares Fitting Cycle-Slip Algorithm Combined With Multiple Cycle-Slip Detection And Repair Methods

In GNSS carrier phase positioning,the generation of cycle slips will cause a large gross error in carrier phase observations,thus affecting the quality of the final navigation and positioning results.The core of this thesis is the detection and repairing of cycle-slip of the tri-frequency datas from BDS,which is mainly based on the principle of the Least-Squares Fitting.It combines the basic principles of the data adjustment field with the multiple mature basic cycle-slip detection and repairing methods.The purpose is to eliminate the shortcomings of the basic cycle-slip detection and repairing methods as much as possible and to combine their advantages,so that this new method we obtained has a better cycle-slip detection and repairing effect on the cycle-slip combinations of various characteristics.We call it the least squares fitting cycle-slip algorithm combined with multiple cycle-slip detection and repair methods.In this thesis,the code-phase combination method,the ionospheric residue method and the MW combination method are selected as the basis of the method we are researching.At the same time,the Least Squares Fitting principle and the indirect adjustment model are selected as the basic principle and model of the cycle-slip detection and repairing calculation.Then the theoretical research on the basic principle,precision index and working steps of the algorithm is carried out.After that we added various types of simulated cycle slips to the actual BDS tri-frequency data(sampling interval is 1S)for conducting related experiments.Preliminary experimental results show that the data itself may contain certain cycle slips when the simulated cycle slip is not added.These cycle slips will affect the final experimental results,which will affect the correctness of our evaluation of the algorithm under research.Therefore,we need to remove these cycle slips first and then continue the relevant experiments.The final experimental results show that:in the case of eliminating the influence of the cycle slips that the data itself may has,this algorithm has a superior cycle-slip detection and repairing effect on various types of cycle-slip combinations for the three-frequency experimental data of the BDS.The accuracy of the detection value of the cycle slips is generally around 0.1 cycles,and the maximum is less than 0.3 cycles,which is very excellent.Simultaneously,The final cycle-slip repair values that we obtained in those experiments is consistent with the simulated cycle slips we added,and there is no error or misjudgment.Finally,we summarize the advantages and disadvantages of this new cycle-slip detection and repair algorithm researched in this thesis and analyze the applicability of this algorithm and what we need pay attention to in practical applications.