Research On Passive TDOA Direction-finding And Location Technology Based On UAV Platform

Starting from the traditional ground passive positioning system,this paper combines the tethered UAV platform and software defined radio(SDR)technology to study the three-station cooperative passive time difference of arrival(TDOA)direction-finding and location technology for ground-based targets,focusing on the algorithm of precise positioning and the source of error in the direction-finding process for the fixed or slowmoving target radiation source on the ground.Based on the tethered UAV lift-off platform,this paper constructs a new three-station coordinated TDOA positioning system for ground-based targets,and analyzes the advantages of the system in specific application scenario,and studies the degree of improvement of the positioning accuracy of the system by effectively eliminating the multipath effect,and studies the working principle and overall test method of the system.The main research contents of this paper are as follows:First,the theory and technology related to passive TDOA positioning such as TDOA positioning principle,time difference measurement technology and time synchronization technology are studied.Then,for ground-based targets,space calibration technology is studied,and TDOA positioning theory applicable to ground-based targets is studied.Secondly,in order to improve the positioning accuracy of ground-based targets,this paper also proposes a three-station cooperative passive TDOA positioning system based on a tethered UAV lift-off platform.The framework of the system is designed,and its working principle is explained.The application scenarios and advantages are analyzed,the test method of the system is studied,and the test flow chart is given.Thirdly,the main sources of errors caused by the TDOA positioning system in the positioning process are studied in detail,and the factors affecting the TDOA positioning accuracy are mainly studied from the aspects of position measurement of reconnaissance station,system timing,time difference measurement,and multipath propagation.Then the calculation method of positioning accuracy is given.Finally,according to the application scenarios involved in this article,two algorithms that can accurately locate the position of the ground-based target are designed,and the two algorithms are simulated and verified,the performance of the algorithms is compared and analyzed;at the same time,the station deployment method of the system is simulated and analyzed,and the positioning results and errors under different station deployment conditions,different reconnaissance station position measurement errors and different time difference measurement errors are studied based on the simulation data.Then the simulation analysis and comparison of the influence of the system error and the error caused by the multipath channel environment on the positioning result are carried out.The results show that the time difference positioning system based on the tethered UAV has higher positioning accuracy than the ground passive positioning system,which can meet the index requirements proposed in this article.The system studied in this paper mainly receives and processes the ultrashort wave and microwave signals propagated by non-cooperative sources within the line of sight,which can better eliminate the multipath effect,and defuzzifies based on prior information such as the relative position of the noncooperative party and the station.Through reasonable arrangement of stations,multiple measurements,and a combination of two algorithms,the positioning error is finally controlled within a smaller range.