Positioning Precision Analysis And Simulation Of "Beidou" System On Passive Mode

This thesis analyzes the principle and architecture of three-star navigation system based on"Beidou"system and investigates the problems related with positioning precision. As well known, such performances as accuracy of satellite-based positioning system are heavily dependent on the number and geometric distribution of satellites being tracked, and GDOP is a right measure of the geometry of the constellation. Therefore in the paper, the impacts of various locations and geometries of pseudo-satellites on the accuracy of the augmented system are comprehensively investigated based on GDOP."Beidou"navigation system is one regional navigation system built by our country, while there are two great drawbacks in it. This system can not accomplish real-time 3-D passive positioning. The position of the user is liable to be detected by enemy and the number of users is liable to be saturated. So the passive ranging mode is considered to improve"Beidou"navigation system."Beidou"navigation system and a geostationary satellite can constitute three-star navigation system. The new positioning system which employs three geostationary satellites emitting radio signals to users just like the GPS satellites do,and allows the users receiver to solve position based on the received radio signal as well as the reading of electronic map,the drawbacks of Double-star navigation system are overcome.In this paper, we deduce the GDOP expression of three-star navigation system. We also discuss the effect of GDOP with the number of satellites. It is also proved in theory that the lowest GDOP using the matrix theory. In practice, we can use GDOP as a reference to locate the pseudo satellites, can also use GDOP to analyze its performance.The improved schemes with adding pseudo satellites based on the actuality to get more observed quantities are presented in this paper and optimum layout of the pseudo satellites is also pointed out. When the position of pseudo satellites is in optimum condition, it can be proved that the way that adding pseudo satellites in the three-star navigation system can really improve the precision of position by comparison and analysis. And the theoretical analysis has been validated by...