Estimation of ICAO Threat Model Parameters For Operational GPS Satellites

Alexander M. Mitelman, Dennis M. Akos, Samuel P. Pullen and Per K. Enge

Abstract:	The ICAO Second Order Step threat model defines a class of signal deformations that present a potential integrity threat to GPS-based aircraft landing systems such as the Local Area Augmentation System (LAAS). The Signal Quality Monitoring (SQM) component of LAAS must have its detection thresholds set at a level which ensures both the required level of safety in the presence of such deformations (integrity) and uninterrupted service under nominal conditions (continuity). The determination and validation of appropriate SQM thresholds requires a detailed understanding of nominal GPS constellation performance. This paper explores the measured performance of healthy satellites in the context of the ICAO threat model. By making direct measurements of the waveforms in the time domain (as opposed to the correlation domain, as is done in conventional receivers), we demonstrate consistent trends among satellites in Block II-A and Block II-R, and overbound all measured satellite signals with waveforms from the ICAO model threat space.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	12 - 19
Cite this article:	Mitelman, Alexander M., Akos, Dennis M., Pullen, Samuel P., Enge, Per K., "Estimation of ICAO Threat Model Parameters For Operational GPS Satellites," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 12-19.
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