GMSK Modulation Uplink Signal Analysis for LAPAN Constellation Satellite using GNU Radio Simulation

Indonesia's geographical location is prone to natural disasters such as volcanic eruptions and tsunamis forces to improve its capabilities and development of satellite communication technology. The Low Earth Orbit (LEO) communication satellite placed on the equator is one of the best choices for Indonesia, considering the small number of satellites in the constellation and the lower cost compared to GEO communication satellites. Modulation for LEO satellites, an important aspect of the communication system, becomes the focus of this research. More spectral efficiency, like the one characteristic of Gaussian Minimum Shift Keying (GMSK), encourages one of the appropriate modulations for communication links in LEO constellation satellites. This paper aims to examine the signal of GMSK modulation on LAPAN's constellation satellites. The result shows that the transmitted signal from the user terminal should be more than 36 dBm to get a −118 dBm signal in the satellite. This paper also explores the link budget comparison for each elevation, which shows that the minimum elevation is 15 degrees using a monopole antenna to establish the link.