If you are looking for solutions that SpaceWire will give you, or for answers to problems you have with SpaceWire, you may be able to find them in 4Links papers. As with our test equipment which is so effective both in detecting bugs and giving you the information to fix those bugs, we try in these papers to give you the information that will help you to build "Networks that Work" and thence to save you bugs, time and money. This page summarizes and links to the papers - on a wide range of topics - that we published or presented in 2007. We hope you find them useful.

"SpaceWire Network Topologies" suggests that SpaceWire's topological flexibility can be used to optimize parameters such as performance, cost, cable-harness mass, or fault-tolerance, or to provide an optimum balance of such parameters for a particular mission. The paper introduces some simple topologies and points to work on earlier technologies such as IEEE 1355 that give useful design insights and may help to get the architecture right early in the project. Presented at the International SpaceWire Conference 2007: paper, presentation.

"Reducing Electromagnetic Emissions from SpaceWire" shows that SpaceWire can generate electromagnetic emissions both within an enclosure and from cables between enclosures. Well-shielded cables and good practice will often be adequate to control emissions, but there may be sensitive applications where further reduction is required. We show that simple techniques can be used to mitigate these undesired effects. Presented at the Data Systems in Aerospace (DASIA) Conference, May 2007: paper, presentation.

"Measuring Time and Time Related Aspects of SpaceWire" presents techniques to measure timing parameters of a SpaceWire device, such as the receive link speed, the times of arrival of Time Codes, the durations and latencies of packets, and the operating margins of the SpaceWire receiver. It points to a number of design defects that have been discovered by such measurements, and how these defects often relate to asynchronous design of the SpaceWire receiver. The paper then shows how the timing measurement techniques can be expanded to cover a large SpaceWire system. Presented at the International SpaceWire Conference 2007: paper, presentation.

The two papers "Ethernet over SpaceWire - Hardware Issues" and "Ethernet over SpaceWire - Software Issues" consider the opportunities for combining the best of SpaceWire, such as modularity, high speed, low latency, fault tolerance, and ease of implementation, with the vast experience of protocol design that has been implemented on Ethernet. The papers then consider how existing Ethernet-based designs can be implemented on SpaceWire networks. These papers were presented at IAC 2006 and were selected for publication in Acta Astronautica in 2007. H/W paper: paper, presentation, as published in Acta Astronautica. S/W paper: paper, presentation, as published in Acta Astronautica.

"SpaceWire Plug-and-Play: An Early Implementation and Lessons Learned" describes a demonstration SpaceWire network that was built before SpaceWire was widely accepted. We showed that SpaceWire could provide a level of fault-tolerance, through redundancy, unmatched by any other technology, yet with a performance some two orders of magnitude greater than previously offered. This was done with a Plug-and-Play system that could be assembled in an arbitrary fashion and continued to work by reconfiguring itself as faults were introduced and spare units brought on-line. The paper describes the demonstration and lessons learned. Presented at the AIAA Infotech@Aerospace Conference and Exhibit, 2007: paper, presentation.

"SpaceWire and IEEE 1355 Revisited" shows that user missions are needing enhancements to SpaceWire to the extent that the missions are already using (non-standard) adaptations from the SpaceWire standard. Several of these aspects, such as DC-balance, power down the cable, and Gbit physical layer, were handled in IEEE 1355, on which SpaceWire was based - but they were discarded in the SpaceWire standard. We suggest that, if SpaceWire is fully to meet user needs, it must evolve to take account of the needs of the missions. Presented at the International SpaceWire Conference 2007: paper, presentation.

 

Please contact 4Links with feedback on these papers and the solutions they suggest.
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