Analysis of Interference to GPS/WAAS by Proposed MSS Spectrum Allocations

Gary A. McGraw, Robert J. Erlandson

Abstract:	This paper presents detailed analyses of the impact to aeronautical GPS/WAAS reception from Mobile Satellite Service (MSS) space-to-earth sources in the band 1559- 1567 MHz proposed at the International Telecommunications Union (ITU) World Radio-communications Conference (WRC) meeting in 1997. Since the 1997 ITU petition for the proposed MSS emissions contained no modulation details, the GPS interference assessment was done with analytical models for the MSS emissions based on signal structures of operational satellite communication services. Several interference modulation cases were considered: wideband noise, 21 kbps random data QPSK, 1 kbps deterministic BPSK, and a CW line spectrum. Ranges of values were used for MSS satellite transmitter filtering and out-of-band intermodulation product levels to test sensitivity to interference spectral roll-off. Realistic assumptions were made for baseline GPS signal and interference levels, and antenna gain patterns. The analysis results demonstrate the possibility for significant degradation to GPS/WAAS performance for aviation users.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	833 - 840
Cite this article:	McGraw, Gary A., Erlandson, Robert J., "Analysis of Interference to GPS/WAAS by Proposed MSS Spectrum Allocations," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 833-840.
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