Design of an adaptive transmitter for a small satellite in the Medium Earth Orbit

Abstract

The volume of data generated by satellites, especially small satellites and CubeSats in the Low Earth Orbit, has drastically increased in the last years. Yet, the limited available RF bandwidth as well as limited resources on small satellite platforms limit the volume of data that can be sent. Thus, adapting the transmission to the current state is considered key since it offers a high level of flexibility. The focus of this thesis lies in the design of an adaptive transmitter system for a small satellite mission whose orbit changes over the mission time. The adaptive transmitter operates in the 10.45-10.5 GHz frequency range with 50 MHz bandwidth. The design of the adaptive transmitter also includes the interaction between the space and the ground segment. In order to optimize the adaptive transmitter, different transmitter architectures, components for the digital and the analogue part, digital signal processing implementations and simulations for the power amplifier module and the antenna are investigated. This comprises the link budget analysis to determine the required Equivalent Isotropically Radiated Power considering the used protocols and standards as well as the evaluation of the link performance in terms of data throughput based on the respective orbit analysis. The different tests for the digital signal processing implementation, for the analogue frontend prototype and for the whole transmitter chain, as well as the evaluation of signal distortions and non-linearities introduced by the analogue components show the feasibility of such an adaptive transmitter for small satellite applications.