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Tham khảo tài liệu 'sensor fusion and its applications part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 294 Sensor Fusion and Its Applications In the absence of noise and interference a single TDOA measurement localizes the emitter on a hyperboloid with the two sensors as foci. By taking additional independent TDOA measurements from at least four sensors the three-dimensional emitter location is estimated from the intersections of three or more hyperboloids. If sensors and emitter lie in the same plane one TDOA measurement defines a hyperbola describing possible emitter locations. Therefore the localization using TDOA measurements is called hyperbolic positioning. The sign of the measurement defines the branch of the hyperbola on which the emitter is located. The two-dimensional emitter location is found at the intersection of two or more hyperbolae from at least three sensors. This intersection point can be calculated by analytical solution see e.g. K. C. Ho 2008 So et al. 2008 . Alternatively a pair of two sensors moving along arbitrary but known trajectories can be used for localizing an emitter using TDOA measurements. In this case the emitter location can be estimated by filtering and tracking methods based on further measurements over time. This chapter is focused on the localization of unknown non-cooperative emitters using TDOA measurements from a sensor pair. Some results have already been published in Kaune 2009 . The localization and tracking a non-cooperative emitter can be improved by combining different kinds of passive measurements particularly in the case of a moving emitter. One possibility is based on bearing measurements. A pair of one azimuth and one TDOA measurement is processed at each time step. The additional AOA measurement can solve the ambiguities appearing in processing TDOA measurements only. Another possibility considers two sensors measuring the FDOA between two frequencies of arrival Musicki et al. 2010 Musicki Koch 2008 . These measurements can be taken by the same sensors as the TDOA measurements. The TDOA FDOA measurement pairs can