Development of GPS L2C Signal Generator for SSV in Geostationary Orbit Simulation

Navigation and timing based on GNSS receivers is widely used in many space missions. The use of multi-constellation and multi-frequency GNSS receivers are expanded to various altitudes of space mission including the GEO mission. However, a GEO satellite equipped with the Satellite Based Augmentation (SBAS) function has a transmitter for GNSS correction signals at the L1 and L5 bands which may interfere with the GNSS SSV receiver at the same satellite. This means, due to the expected strong interference, GNSS signals at the L1 and L5 bands cannot be used for the GEO SBAS satellite, and the use of GPS L2C signals can be considered as an alternative. This paper presents the development of GPS L2C signal generator for SSV in GEO simulation. The GPS L2C signal simulation process for GEO satellites and the structure of the GPS L2C signal generator are presented. A verification through the receiver test with a GNSS SDR is included to show the feasibility of the designed signal simulator. The validation is performed by analyzing the PSD, the results of acquisition, code/carrier tracking, and C/N0 estimation.