Design and Implementation of a TM/TC Software System of the Nano Satellite AISat/Clavis‐1

Abstract

Data & Command Handling is one of the main tasks of satellite software. A lot of interpretations exist on how to implement a reliable software module and many of them seem to be very complex and thus not feasible for a nano satellite system. This paper describes the challenge of such a development and goes into detail of particular aspects and limitations. Thereby it focuses on the development and Implementation of a TM/TC software system of the nano satellite AISat. AIsat is a nano satellite project at the DLR institute of space systems and its main objective is the satellite-based support of AIS data processing as well as a demonstration of a 4 meter deployable helix antenna experiment. The satellite is based on the CLAVIS bus platform. CLAVIS was developed by a DLR working group to introduce a modular and flexible bus for the accommodation of different payloads in the nano satellite class. Its main concept is to adopt COTS components for space business to speed up development and lower the costs of access to space. Through its compact but still effective software design, the TM/TC module of CLAVIS tries to answer code size related issues but at the same time to ensure a secure handling through the satellite operator. Mainly the TM/TC software contains a command manager, which is responsible for the validation, Interpretation and distribution of telecommands. Different mechanisms and concepts provide a scheduling of the command execution but also protect it against erroneous command sequences and errors coming through the unreliable RF communications uplink.