Study On Technologies Of Localization Using TDOA And FDOA Of Unmanned Aerial Vehicles

Locating ground emitters passively, accurately and fast, is an important problem in the fields of reconnaissance, early warning, surveillance, salvation and so on. Localization using Time Difference of Arrival (TDOA) and Frequency Difference of Arrival (FDOA) of two aerial vehicles has been deeply researched for its simple structure and high localization precision, and has been paid widely attention to recently. Moreover, Unmanned Aerial Vehicle (UAV) will play an important role in the information obtain of future warfare for its smallness and lightness. In order to satisfy the requirement of applying localization using TDOA and FDOA on the platform of UAVs, some specific technologies such as respective estimation of TDOA and FDOA, algorithm and precision analysis of localization using TDOA and FDOA, optimal trajectories of UAV are researched in this dissertation. The research strongly supports the engineering application of localization using TDOA and FDOA on the platform of UAVs.In chapter 2, the mathematic model of narrowband signals with TDOA and FDOA is built, the Cramer-Rao Lower Bounds (CRLB) for TDOA and FDOA estimation is calculated. And then, algorithm of TDOA and FDOA estimation is improved using the idea of estimating TDOA and FDOA respectively. At last, specific approach is presented and the availability of the algorithm and reduction of computational complexity are indicated by the computer simulation.In chapter 3, two models of localization using TDOA and FDOA are studied. One model is sampling analog signals to digital codes on the UAVs, and the other is transmitting analog signals directly to the command station on the ground. The localization equations of both these two models are built, algorithms of localization are deduced, localization precisions are analyzed. The availability of the algorithm is proved by the computer simulation and the Geometrical Dilution of Precision (GDOP) distributions of typical scenes are presented. According to the situation that the Direction of Arrival (DOA) of the signal is obtained, the algorithm of united localization both using TDOA/FDOA and orientation conical angles based on Gauss-Newton Iteration (GNI) is proposed, and localization precision is analyzed. The computer simulation proves that the localization precision of united localization adding the DOA of signal, is higher than the localization precision of localization only using TDOA and FDOA.In chapter 4, localization GDOP distributions of the situations that two UAVs fly in different manners are simulated, and the flying manner by which the best localization precision is obtained when the signals last short is presented. As for the situation that the signals last longer, the algorithm of single-step optimization of UAV trajectories based on minimizing GDOP is proposed. The computer simulation proves the localization precision is improved by using the algorithm.The theme of this dissertation is the application of localization using TDOA and FDOA on the platform of UAVs. Some important technology problems of engineering of localization using TDOA and FDOA are studied. Theoretical analysis and computer simulation result of the algorithm presented in this dissertation can guide practical engineering effectively.