Optimal geometric allocation of ground stations for navigation satellites

Precise orbit determination of navigation satellites is very important to provide accurate positioning information to the ground users. Measurement errors should be minimized to get precise orbit trajectory. A couple of ground stations are required to obtain range data using radio or SLR(Satellite Laser Ranging). However, it is very difficult to ensure observability with ground stations located inside Korean peninsula for high altitude satellites such as HEO(High Earth Orbit) or GEO(Geostationary Earth Orbit) satellites. This paper presents a comparative study on the measurement errors for the precise orbit determination of navigation satellites according to the location of the ground stations. A new method of positioning ground stations to uninhabited areas such as north or south poles and/or relevant area is proposed, and the effect of additional locations of the ground stations are investigated. Ground stations located in higher latitude are extremely useful to obtain quality range data for HEO/GEO satellites because they have high elevation angle when they are used in combination with the ones located inside the Korean peninsula. Optimal geometric locations and numbers are sought via comparative study in the pools of candidate locations. Common error sources such as troposphere errors are considered to extract best locations for ground stations.