| The global navigation satellite system can provide all-weather and high precision position,velocity and time information and realize the positioning,navigation and timing.In this paper,the global navigation satellite system positioning algorithm is studied,which includes the follow aspects:Firstly,the errors of satellite,propagation and receiver and satellite geometric distribution have an effect on positioning accuracy.This paper adopts the accuracy of the attenuation factor coefficient to represent the position error magnification and determines the relationship between different time satellite number and position accuracy.The influence on different epochs on the accuracy of positioning is analyzed by the simulation results.Secondly,different algorithms have different positioning accuracy in solving user location coordinates.This paper uses the genetic algorithm and hybrid genetic algorithm to solve the nonlinear equations and determine the location coordinates,which based on Newton iterative method and least squares method.In the positioning calculation,Newton iteration and least squares method are solved by iterative method.Among them,the least square method can solve the overdetermined equations in positioning,which brings more convenience to the solution.The genetic algorithm can achieve fast convergence of the positioning results,the quasi-Newton method in the hybrid genetic algorithm can further converge the results of the genetic algorithm,which can improve the stability of the positioning.In addition,this paper adopts the method of differential positioning to reach the requirement of high precision positioning.The pseudo-range differential positioning can eliminate the errors of the ionosphere,the troposphere residual and the receiver clock and improve the positioning accuracy.The positioning accuracy can reach sub-meter level by re-differentiating the pseudo-range double difference based on the pseudo-range single-difference positioning,so the positioning accuracy can be greatly improved.Finally,the simulation results can meet the precision requirement and achieve the desired objectives by MATLAB simulation validation of different algorithms. |
