Design Concepts for a Highly Reliable Multimicroprocessor System for Communication Satellites

Abstract

Over past years, the microprocessors have been used widely and efficiently for many applications. Some of them have become industrial standards, and the question arised how to use them most efficiently for space applications. The paper describes the design concepts which have directed the study and the breadboarding of a trimicroprocessor system and its monitoring software. These concepts have been traded off for reaching a high system overall availability and flexibility. The multiprocessor is organized around C-MOS microprocessors and a time shared/common bus, designed for reliable operations. The monitoring software is especially developed to yield a triple redundancy for critical (i.e. mission success dependent) software functions and to assure the mutual failure independency of the application programs. On board telecommunication satellites, the multiprocessor structure have been found better suited for reliability, probability of mission interruptions and its capability of degraded operation when it was compared to a classical stand by redundant monoprocessor array. At the end of the year, the triprocessor system will be integrated into a satellite attitude control simulator for a system closed-loop test with an air bearing table and actual satellite equipments.