Integrated and Modular Systems for Commercial ... - Nonstop Systems

EMC: Electro-Magnetic Compatibility
• increased EMI-susceptibility of electronic devices:
� integration: higher chip density; (deep) sub-micron feature sizes
� reduced operating voltages
� lower levels of energy cause upsets
• increased reliance on digital computers (for flight-critical
functions) that contain EMI-susceptible devices
• higher clock speeds:
� reduced susceptibility: PCB tracks become transmission lines
� but absolute bandwidth for decent signal shapes goes up (≈10xfc)
� though bandwidth pushed into range with fewer x-mitters (civil)
• continued proliferation of EM transmitters (incl. PEDs),
and increase in EM power
• reduced inherent Faraday-cage protection: increasing
amounts of non-metallic airframe sections
ref.: C.A. Clarke, W.E. Larsen: “Aircraft Electromagnetic Compatibility”, Feb. ‘89, 155 pp., DOT/FAA/CT-88/10; same as Chapt. 11 of Dig. Systems Validation Handbook Vol.
II
ref.:G.L. Fuller: “Understanding HIRF - High Intensity Radiated Fields”, Avionics Comm. Publ., Leesburg/VA, ‘95, 123 pp., ISBN 1-885544-05-7
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ref.: M.L. Shooman: “A study of occurrence rates of EMI to aircraft with a focus on HIRF”, Proc. 12th DASC, Seattle/WA, Oct. ‘93, pp. 191-194
©1995-1997 F.M.G. Dörenberg