Research On Key Technical Problems In Beidou High Precision Positioning

Beidou Satellite Navigation System is a basic positioning and navigation system built independently in China.Considering the military security and social and economic benefits of our country,it makes our country have a more long-term development.In recent years,the establishment of Beidou system in China is improving step by step,and the scope of service is also expanding.The use of Beidou system and its related products has been more and more deeply into people's daily life,which has great significance for improving national economy and promoting social development.The research of Beidou satellite precise positioning technology is becoming more and more important.In this paper,the problems of pseudo ranges positioning and carrier phase positioning in Beidou positioning are analyzed and probed,the main research work contents are as follows:Firstly,pseudo ranges positioning technology is used to calculate the receiver's position initially in precise positioning,introduces the principle of pseudo ranges positioning,analyses the positioning algorithm of pseudo ranges.Firstly,the least square method is used to solve the positioning problem,then research the Kalman filtering algorithm and both the two methods are based on linear system.Secondly,the positioning algorithm model of Beidou Positioning System is nonlinear,it studies the Unscented Kalman filter and probes its advantage of the positioning calculation result is obvious.At the same time,the improved Unscented Kalman filter is proposed in this paper,and the method is based on traditional positioning algorithms and it has a real-time estimation of noise in positioning by using the noise estimator.The method gets a better adaptability,convergence and an upgraded positioning accuracy.Thirdly,about the problem of the cycle slip in the positioning process of Beidou satellite system,the classical detection methods are be studied and verified firstly,and then probes into the detection performance of the classical methods for different cycle slips.And the paper researches the combination cycle slip detection character of the triple frequency carrier phase.Compared with single and double frequency,there is a wider application range and a higher detection accuracy of the triple frequency combination detection methods.Finally,the code-phase combination joints the geometric-free and ionospheric-free phase combination to detect the cycle slip in this paper.The geometric-free and ionospheric-free phase combination can eliminate the error of the ionosphere and pseudo ranges.According to the observation of the combination method and optimal principle,three sets of the qualified combination observations are selected.The experiments which is based on the Beidou satellite show that the method in this paper can detect cycle slips of various combinations.