Research On Key Technologies Of Positioning On Multi-mode Satellite Navigation Receiver

With the development of the Global Navigation Satellite System(GNSS),The GNSS currently in operation include the Global Positioning System(GPS),Galileo Satellite Navigation System(Galileo),GLONASS,and Beidou Satellite Navigation System(BDS).Compared with single GNSS,multi-GNSS has many advantages,such as obtaining more visible satellites,better positioning accuracy,and higher reliability.However,the computational cost of a receiver is significantly increased.Therefore,how to improve the speed of satellite selection and the efficiency of positioning solving,while ensuring the user’s positioning accuracy requirements,is becoming a key problem that needs to be urgently solved in the current navigation field.The main research results of this thesis are as follows:1.Aiming at the shortcoming(a large amount of computation)of the traditional traversal satellite selection method that uses Geometric Dilution Precision(GDOP)characterizing the quality of satellite geometric space configuration as the satellite selection index,this thesis chooses GDOP as the critical factor and combines it with Genetic Algorithms(GA),proposing a satellite selection model suitable for multi-GNSS.The simulation results confirm that the GDOP-GA satellite selection model is feasible.This method has the following characteristics:(1)Encoding the solution by using “natural encoding” method;(2)Replacing the traditional method,uniformly distributed sequence,with Sobol sequence;(3)Giving the definition of mature factor and integrating mature factor into crossover and mutation operations;(4)Performing selection operations based on a multi-pointer wheel;(5)Proposing a cure operation.Based on the basic framework of the GA satellite selection model,this thesis optimizes the threshold of reproduction algebra and introduces a hunting strategy to improve the efficiency of GA.The simulation results show that the threshold of reproduction algebra can be set to 50,and the hunting strategy has the function of improving the efficiency of GA.2.To solve the problem that traditional positioning solution methods based on the Taylor series have large amounts of calculations,this thesis proposes a decoupled leading term elimination positioning method based on the solution of polynomial equations.Compared with the least squares method,its relative error order of magnitude is-14,and it has the same accuracy as the least squares method with respect to the truth value of user’s position.The decoupled leading term elimination positioning method has the feature that gives an analytical expression of the localization solution while ensuring the localization accuracy,without the need for initial value selection and iterative computation of user coordinates.