Performance Enhancement of Hybrid TDOA/AOA Using Multipath Delay Estimation

During the launch mission of a launch vehicle (LV), localization of the LV is very important for ensuring flight safety. Usually, active localization systems such as the ground tracking radar systems and onboard navigation systems of the LV are responsible for acquiring the relevant location information for localization. However, if, in addition to the existing localization methods, passive localization using ground telemetry stations can be implemented, the reliability of the flight safety control for the LV can be improved. Time of arrival (TOA), time difference of arrival (TDOA), and angle of arrival (AOA) are typical localization techniques used for an emitting target. In this paper, we examine passive TDOA/AOA localization that uses two ground telemetry stations, and propose a technique to improve its localization accuracy, based on second-order polynomial regression and the removal of the estimated multipath delays in the TDOA/AOA results. By comparing the results of our proposed technique with the measured data from an on-board GPS used in the 3rd Korea Space Launch Vehicle-1 (KSLV-1) mission, our study confirms that the localization accuracy has been improved.