Research Of Positioning System By Ground-Based Pseudolite With GNSS

With development of satellite navigation and positioning technology and the continuous reduction of the cost of hardware,navigation and positioning technology has entered everyone's life.As the most comprehensive positioning technology,GNSS has become more and more precise because of the increase of GNSS in-orbit satellites.However,in some specific scenarios,the satellite signal will still be interfered,caused by an insufficient number of visible satellites,the accuracy and stability of location cannot be guaranteed.Pseudolite technology makes up for som e GNSS deficiencies,so it has been widely studied.There are also some shortcomings in the pseudolite system.This paper solves the problems in the application of pseudolite by studying the integrated positioning of GNSS and pseudlite.It mainly includes the following contents:1.We introduce the composition and positioning principle of the ground-based pseudolite position system.The positioning system consists of pseudolite base station and pseudolite receiver.The system uses Software Defined Radio pla tform,and including industrial computer module,the IF channel module and the RF channel module realizes the functions of signal transmission,signal reception and positioning.2.In order to solve the problem of the initial position of pseudolite,we did the research the integrated positioning mode of GNSS/INS,and designed the mode of pseudolite/GNSS integrated positioning for initial position.First,we analyzed the reason of the problem of initial position and the feasibility of GNSS to solve the problem.Then,in order to reduce the interference of noise,a second-order digital filter is designed to filter the initial value,and the filtering effect is verified.3.Aiming at the problem of insufficient number of visible satellites under special conditions for ground-based pseudolites the pseudolite/GNSS combination was designed by studying the integrated positioning of two major positioning systems within GNSS with the same positioning principle.The integrated positioning method is used to solve the problem of positioning accuracy degradation caused by the lack of visible satellites under special conditions.4.The station selection method of integrated positioning is researched.We compared the similarities and differences of the GNSS system's station selection method,proposed a station selection method using weighted dilution of precision instead of dilution of precision as the basis way of selecting the station.The performance of the station selection method was verified by simulation.5.We tested the pseudolite/GNSS integrated positioning system that we design.The test result shows that the accuracy of the initial position of pseudolite/GNSS integrated positioning system meets the requirements of engineering applications.The pseudolite/GNSS integrated positioning system can guarantee the maximum positioning accuracy when the pseudolite is not enough satellites and meet the disign requirements.