Performance Analysis of 3D Localization for a Launch Vehicle Using TOA, AOA, and TDOA

In general, a ground telemetry station for a launch vehicle (LV) includes a tracking function only; therefore, position measurements for LV depend on received navigation data from on-board systems of LV or depend on estimated position from ground radar system in real time. At the first launch of the Korea Space Launch Vehicle-1 (KSLV-1) in August 2009, we observed anomalies in ‘pairing separation’ event. As a result, we failed to obtain stable navigation data of the LV. In addition, estimated positions from the radar station away 1000 km to the LV also included many errors due to low antenna elevation angle. The experiences of failure has led to needs for additional localization solutions in ship-born telemetry station deployed in the Pacific to cover ‘satellite separation’ event. Time of arrival (TOA), time difference of arrival (TDOA), and angle of arrival (AOA) are typical location techniques used for an emitting target. In this study, we analyze three localization methods: TOA–AOA, AOA–AOA, and TDOA–AOA for a LV using ground telemetry stations. When each ground station is synchronized to a GPS time, by comparing the time stamps of each receiver (Rx), TOA and TDOA equations can be obtained. In addition, AOA equations can be obtained from the monopulse tracking antenna of each station. By solving these equations, a three-dimensional (3D) target point can be obtained. We confirm localization performance of the proposed solution by comparing with an on-board GPS of 3rd KSLV-1 mission in January 2013.