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Towards a distributed real-time system for future satellite application

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dc.contributor.advisor Du Plessis JJ, Prof en
dc.contributor.author Rozendaal A en
dc.date.accessioned 2016-09-22T08:34:31Z
dc.date.available 2016-09-22T08:34:31Z
dc.date.submitted 2003 en
dc.identifier.uri http://hdl.handle.net/20.500.11892/31016
dc.description.abstract The Linux operating system and shared Ethernet are alternative technologies with the potential to reduce the development time and costs of satellites as well as the supporting infrastructure. Modular satellites, ground stations and rapid prototyping test-beds also have a common requirement for distributed real-time computation. The identified technologies were investigated to determine whether this requirement could also be met. Various real-time extensions and modifications are currently available for the Linux operating system. A suitable open source real-time extension called Real-Time Application Interface (RTAT) was selected for the implementation of an experimental distributed real-time system. Experimental results showed that the RTAI operating system could deliver deterministic real-time performance, but only in the absence of non-real-time load. Shared Ethernet is currently the most popular and widely used commercial networking technology. However, Ethernet wasn't developed to provide real-time performance. Several methods have been proposed in literature to modify Ethernet for real-time communications. A token passing protocol was found to be an effective and least intrusive solution. The Real-Time Token (RT-Token) protocol was designed to guarantee predictable network access to communicating real-time tasks. The protocol passes a token between nodes in a predetermined order and nodes are assigned fixed token holding times. Experimental results proved that the protocol offered predictable network access with bounded jitter. An experimental distributed real-time system was implemented, which included the extension of the RTAI operating system with the RT-Token protocol, as a loadable kernel module. Real-time tasks communicated using connectionless Internet protocols. The Real-Time networking (RT-net) subsystem of RTAI supported these protocols. Under collision-free conditions consistent transmission delays with bounded jitter was measured. The integrated RT-Token protocol provided guaranteed and bounded network access to communicating real-time tasks, with limit overheads. Tests exhibited errors in some of the RTAI functionality. Overall the investigated technologies showed promise in being able to meet the distributed real-time requirements of various applications, including those found in the satellite environment. en
dc.language English en
dc.subject Electrical and Electronic engineering en
dc.title Towards a distributed real-time system for future satellite application en
dc.type Masters degree en
dc.description.degree MSc en


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