Standard Telemetry Processing – an object oriented approach using Software Design Patterns

Abstract

While rapidly increasing the software safety and reliability requirements of space-born satellite missions the reduction of processing software development costs is of global interest. To achieve the mission goals both the quality of the applied program design and implementation have a remarkable influence. Because remote sensing data processing software is highly complex and costs a lot to develop, reusing software helps to economize payments significantly and creates maximum benefit to meet quality needs. For the small satellite mission CHAMP the Packet Telemetry Recommendation of the European Space Agency ESA gave the main idea to develop an object-oriented program design of an on-ground data processing system. Due to several on-board satellite instruments (sensors, optical cameras etc.) the amount and the structure of the remote sensing data is completely different. This, of course, requires satellite specific converting algorithms, and with the above mentioned recommendations only standard processing steps can be performed. However, when considering future satellite projects the software design to use must be tailored to the mission specific requirements of the application data handling only. This paper shall report the application of object-oriented software design within the CHAMP project. Based on the Telemetry Packet Standards, the hierarchy of abstract classes is a joined application of the Design Patterns `abstract factory' and `facade'. The growth of flexibility as well as the limitations of their use are discussed with implementation examples. The reuse of both the software architecture and the abstract base classes is also planned for the small satellite mission BIRD.