En-route Multilateration System Based On ADS-B And TDOA/AOA For Flight Surveillance Systems

With the rapid development of the aviation industry,the air traffic flow has experienced explosive growth in the last ten years.The fast growing passengers and flights pose higher requirements for the civil aviation industry and the corresponding surveillance technologies.Due to the relatively low precision,narrow coverage,and high cost,the traditional surveillance facilities based on radars will be limited to meet the demands of the future.The automatic dependent surveillance broadcasting(ADS-B)is a promising technique and its application to aircraft surveillance has formed a consensus.However,the multilateration(MLAT)based on ADS-B is in the initial stage of development and the related researches are mostly focusing on the airport scenarios.The existing positioning methods are based on time difference of arrival(TDOA)only when using the technology of MLAT based on ADS-B signal to track the aircraft on the route.A hybrid enroute ADS-B/MLAT positioning algorithm based on TDOA and the angle of arrival(AOA)is proposed by introducing the AOA.Firstly,we introduce the concepts of TDOA and AOA.Then,the constant velocity(CV)model and the coordinated turn(CT)model,which are both in the aircraft dynamic flight model and used to characterize the motion state of the aircraft when the aircraft on the route,are discussed.This thesis comprehensively uses Extended Kalman Filter(EKF)to process the different measurements and adopts the IMM theory to switch between multiple motion state models.We propose an algorithm to determine the relatively optimal coordinates of receivers for the scheduled route when using the ADS-B/MLAT positioning system to track the aircraft on the route.This algorithm transforms the problem of determining the coordinates of ground stations into an ergodic permutation problem and the relatively optimal coordinates can be found by traversing the grid points.This thesis sets up an ADS-B omnidirectional antenna in Nanjing University of Posts and Telecommunications to receive the ADS-B signals,and experiments cover both simulation data and actual data received by our ADS-B platform.Finally,the experimental results show that the relatively optimal coordinates algorithm can find the receivers’relatively optimal coordinates,and the accuracy of the hybrid ADS-B/MLAT based on TDOA/AOA has improved by 88.21%and 57.34%in the horizontal direction compared with the ADS-B/MLAT system based on TDOA when use simulation data and real ADS-B messages.