The Impact of Interference on Civil GPS

Robert S. Littlepage

Abstract:	The rapidly increasing dependence on GPS within the civil community, and particularly within the transportation sector, has created an urgent need to recognize the fact of the vulnerability of C/A code to interference. This may take the form of accidental interference (EMI) or deliberate interference (jamming), either of which would have severe economic impact on our nation’s commerce. For example, can we afford to contemplate an aviation safety infrastructure based solely on GPS. This paper will primarily deal with deliberate interference. A model will be described which accurately predicts the impact of jamming on GPS-C/A, with example cases based on very low power jammers (10-100 mW). These results will be used as the basis for examining the effectiveness of various anti-jam technologies available to the civil users: body masking; specialized antennas; flight geometry; filters; etc. A very cost effective ferrite based filter will be described, including its’ C/A code measured performance against a wide variety of jammer types (CW, AM/FM CW, broadband noise, etc.).
Published in:	Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999) June 27 - 30, 1999 Royal Sonesta Hotel Cambridge, MA
Pages:	821 - 828
Cite this article:	Littlepage, Robert S., "The Impact of Interference on Civil GPS," Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999), Cambridge, MA, June 1999, pp. 821-828.
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