Development and Assembly of Measurement Setup for Assessing the Magnetic Behavior of SpaceWire Links

Abstract

An indefeasible part of any space mission design is the interconnecting wiring of the mission’s units. As a result, any emissions produced by the latter are of vital importance regarding the Electromagnetic Compatibility of the whole spacecraft design. The development of the SpaceWire standard has proven very advantageous for the space industry as it aims to standardize the process of creating a wired network in a spacecraft. The former, enhances the reusability of already developed components, making them compatible with new missions and therefore reducing their cost. Nevertheless, the widespread implementation of the SpaceWire standard has also increased the importance of assessing the potential for electromagnetic interference produced by a SpaceWire network. Towards this goal, within the context of the project “Modeling Electromagnetic Emissions of Space Equipment for EMC and Cleanliness Purposes” realized by the Wireless and Long Distance Communication Laboratory (WLDCL) of the School of Electrical & Computer Engineering of the National Technical University of Athens, the current thesis aims to develop a setup for measuring both the static and the ELF magnetic field emissions caused by the operation of a full-duplex SpaceWire link. Through these measurements, the potential for magnetic field emissions from the link will be evaluated and a thorough examination will be made to identify any correlation between the emissions’ level and some of the transmission’s characteristics. For the formation of the SpaceWire link, a suitable cable assembly is utilized in conjunction with an instrument simulating the interconnected nodes. The magnetic field emissions of the link are monitored, for several sets of link characteristics, with the use of two triaxial fluxgate magnetic field sensors. Any low frequency magnetic field emissions produced by the operation of a SpaceWire link can be attributed, inter alia, to alternating currents flowing through the ground loop, caused by the termination of the outer shield of the cable assembly. These currents can be induced to the conductive shield through inductive couplings between the latter and the signal carrying twisted wire pairs. Nonetheless, for a more complete analysis, several additional potential emission mechanisms will be discussed. The lack of any specialized magnetic shielding in the area of the measurements will be negated by the employment of a suitable measuring technique, in order to differentiate between the ambient field’s components and any emissions caused by the operation of the link. Overall, an assessment of the behavior of the link regarding its static and ELF magnetic field emissions will be presented and some additional tests for future analysis will be proposed.