Comparison of AOA Localization in Ultrashort Wave under Various Azimuth Calculation Methods

Given that azimuth calculation is fundamental to angle-of-arrival (AOA) localization, the spherical approximation method and normal cylindrical projection-plane method for azimuth calculation on geodetic coordinates are proposed firstly. Furthermore, the AOA localization equations based on spherical accuracy calculation, spherical approximation calculation, and normal cylindrical projection-rectangle are established respectively. Finally, the unconstrained nonlinear programming method is used to establish the three optimization AOA localization models on geodetic coordinates, which correspond to the above equations respectively, and the models are verified by the point-by-point grid search method. The numerical results show without considering the direction-finding error, the spherical accuracy AOA localization model has the highest precision, which is independent of latitude, but its positioning operation time is the longest. As for the spherical approximation AOA localization model and the normal cylindrical projection-rectangle AOA localization model, both have a high precision, the positioning error of the latter is slightly higher than that of the former, and its positioning operation time is also longer than that of the former. The positioning accuracy of AOA localization network can be improved by increasing either the direction finding accuracy of each site or the number of direction finding sites. The appropriate AOA localization model is selected according to the overall positioning requirements of the timeliness and precision.