A Software-Defined Radio Transmitter for Variable-Coded Modulation on a CubeSat

Abstract

The large volume of satellites sharing the same spectrum and the complexities of communications in Low-Earth Orbit (LEO) pose challenges to the downlink of large volumes of data on a platform that is bandwidth, power, and time limited. LEO satellites operate in a highly variable communications environment due to variations in inter-satellite or satellite-to-ground geometries, weather, and interference. Therefore, there is motivation for implementing satellite communication techniques that manage these issues to increase the data throughput. One such technique is variable-coded modulation which shows improvement by taking advantage of the dynamic nature of a satellite link. As part of the Air Force Research Laboratory University Nanosatellite Program, and in collaboration with NASA, this project focuses on the development of an S-band software defined radio for CubeSats that utilizes variable-coded modulation defined by the Digital Video Broadcasting-Satellite-Second Generation standard. This project defense discusses the initial development and testing using GNU Radio, and the challenges for full implementation, as well as the current status of the transmitter, and future work.