Design and Implementation of a Software-Defined-Radio Based Telemetry System for Deep Space Applications

The growing number of space missions adopting small satellites platforms, together with the request of larger data rates, points out the need for efficient software-defined radios providing high reconfigurability. For this reason the Italian aerospace company Argotec has undertaken the development of a software-defined radio transponder for deep space applications, named ERMES. This thesis is focused on the development of the telemetry subsystem for the ERMES transponder. In particular the physical and coding layer will be implemented, focusing on system reconfigurability and compatibility with CCSDS standards. The different components of the transmission chain will be investigated, paying attention to possible hardware-oriented implementations. The first block which will be analyzed is the encoder. In particular two different coding schemes will be considered: Turbo and Low Density Parity Check codes. Then, an analysis concerning the shaping filters will be carried out, with the purpose of determining a suitable digital domain implementation. At this point the modulator will be considered. Several modulation schemes of different nature will be investigated, comprising subcarrier modulations, residual carrier modulations, and suppressed carrier modulations. The whole transmission chain will be first implemented in C/C++ language and compared to an already available MATLAB simulator. Then the developed C/C++ simulator will be run on a software-defined radio device from the USRP family and measurements will be performed through a signal analyzer in order to check the correctness of the transmitted signal.