The GNSS receivers, which utilize RF signals from external navigation satellites to obtain position and time information are widely used for range safety as well as navigation in space launch vehicles. It is necessary to analyse the visibility of GNSS satellites since the GNSS system in KSLV-I which is used for range safety sensor utilizes the navigation signals from the Earth orbiting satellites. It is general that GNSS system in space launch vehicle needs 2 or more antennas to obtain enough visibility because the antennas are installed toward horizontal plane. And the attitude of a space launch vehicle varied with time should be considered in visibility analysis. This paper describes the visibility analysis of GNSS satellite using 3rd flight test data of KSLV-I.

Keyword: KSLV-I, GNSS, visibility analysis, attitude