The Research And Software Implementation Of Positioning Calculation Algorithm For Beidou Navigation System

Beidou Navigation System is one of the major space infrastructures in China,its development has great significance to the promotion of Chinese economy and national security.The technology of satellite navigation positioning aims to provide positioning service for different users,therefore the research and software implementation of positioning solution module in navigation receiver has always been focus of study in the field of satellite navigation positioning.Based on this research status,this thesis lays emphasis on the development of positioning solution algorithm and the software realization of positioning solution module.Firstly,this thesis gives a general introduction of Beidou Navigation System,introducing its composition,its satellite signal characteristics,its time system and its coordinate system.Next,it illustrates the fundamental principle of pseudorange positioning and designs an implementation scheme for the whole positioning calculation module.Then,it introduces beidou observation files and navigation files,discussing how to obtain navigation parameters from the two types of file.Then,it provides a methods of calculating satellite position and modifying pseudorange by using those parameters and proves the correctness of the proposed method by simulation on the matlab platform.On the basis of the above research,the paper gives a detail introduction about three commonly used algorithms in positioning calculation and analyzes their performance by simulation.The simulation result shows that the kalman filter has the highest positioning accuracy.Then,the kalman filter algorithm is emphatically researched.By analyzing kalman filter results with different initial filtering values,it finds that a more precise initial filtering values can help make filtering results quickly stabilize,so the thesis proposes to use result of alpha_beta filter as the initial value of kalman filter.By discussing the cause of the filtering divergence,the thesis presents a new way to decrease the filtering divergence influence of kalman filter.The new way abandons the current kalman filter results when it finds the current kalman filter result tends to diverge.Simulation result shows that the modified method can effectively suppress the divergence problem in kalman filtering.Besides,the thesis designs a C++ software of Beidou positioning module based on VS 2012 platform and MFC development framework.The whole design can be divided into two part: the interface module and the background programming module.The designed software interface can fully display the results of pseudorange extraction module,satellite location module,location algorithm module.By utilizing the object-oriented programming method,the thesis packages each part of positioning calculation module into a class and its function.When the software is running,you can see the positioning results of each moment in the interface after importing observed and measured files into the software.Compared with the results with the real position of user,the two results are consistent,which proves the designed software is useful.