Research On Differential Satellite Positioning Technology And System Based On Multiple Base Stations

With the rapid development of global satellite positioning technologies,satellite positioning technologies and systems have been widely applied in various fields.The United States' Global Positioning System(GPS)has many advantages,and its technology is mature.It has been widely used in the world,but GPS single point positioning cannot meet the requirements of high-precision positioning.Differential satellite positioning technology has also been rapidly developed on this basis.Among the three differential methods,compared with position difference and carrier phase difference,pseudorange differential positioning accuracy is suitable for civil life needs,and implementation is relatively simple.The differential satellite positioning system has also evolved from the single base station differential positioning system to the current multi-base differential positioning system.Since the single base station differential positioning system has a single base station and the scope of its role is very limited,as the distance increases,the atmospheric correlation error decreases.As the positioning accuracy decreases,it is of practical value and significance to study multi-base differential systems.Based on the differential GPS positioning technology,this paper makes an in-depth study of differential satellite positioning technology and system.The basic principles of GPS differential satellite navigation and positioning are analyzed in detail,and three kinds of differential positioning methods are experimentally analyzed.This paper mainly studies differential satellite positioning technologies and systems based on multiple base stations.The multi-base station differential satellite positioning system in this paper is to distribute multiple base stations in different areas.The base station is designed first,and the GPS receiver is combined with the Raspberry Pi and connected to the server.Each base station is a base station with a server.The basic principle of the existing single base station or multiple base stations is the same,and only the satellite raw data or differential correction values are transmitted.In this paper,a base station server selection algorithm is proposed for multiple base stations,which can select the nearest base station as a base station to perform differential positioning for the user mobile station.The mobile station only sends the request query information and the current approximate location to the base station through the network.After receiving the data of the mobile station,the base station server evaluates the mobile station and selects the nearest base station for the mobile station to perform differential positioning.In this paper,the pseudo-range differential positioning technology is used to achieve the extended Kalman filter positioning of pseudo range differentials.Compared with pseudo-range differential least squares positioning,a contrast is made and the positioning results are smoother.In order to make the positioning result more smooth and accurate,this paper proposes an extended Kalman filter localization with pseudorange differential and Doppler shift differential combination.The Doppler shift difference and pseudorange difference combination are used to perform optimal fusion positioning by extended Kalman filter.Finally,based on this multi-base station differential satellite positioning technology and system,a series of tests and experiments are conducted.The test shows that the design of the base station meets the requirements.The experimental results show that the multi-base differential positioning system has better positioning accuracy than the single base station differential positioning system.The feasibility of the server selection algorithm and the necessity of the arrangement of multiple base stations are verified.Experiments show that the proposed extended Kalman filter positioning based on pseudo range differential and Doppler shift difference can make the positioning result more smooth and accurate,and the short baseline positioning accuracy is within 1m.The positioning system provides reliable theoretical and practical support for applications such as vehicle driving,drones,and smart phones.