Satellite Acquisition for a Strike Missile Under Jamming and Time Initialization Constraints

Charles Behre, Renato Ornedo, Gaylord Rogeness, and Todd Moore

Abstract:	Guidance systems using the combination of GPS and INS are good candidates for strike missile type weapons. The accuracy of this system is highly dependent upon acquiring GPS signals before a specific point in the trajectory. This paper describes an analysis approach to determine the GPS satellite availability with Time To First Measurement (TTFM) constraints and severe jamming conditions. The TTFM for direct acquisition of Y-Code increases as the accuracy of an initial timing reference decreases and as a receiver’s PDI and dwell time settings increase. Furthermore, the receiver can only acquire satellites with signal–to-noise levels above a certain threshold. In the presence of jamming, the movement of the vehicle body changes the resulting jammer-to-signal levels along the trajectory, greatly influencing the probability of acquiring GPS signals. The resulting satellite availability is dependent upon constellation geometry, performance of jamming mitigation, and the acquisition times of the receiver. The data presented in this paper are for strike missile type trajectories in a jamming environment using a null-steering jamming mitigation technique. The trade space that is examined includes trajectory range, satellite signal power, initial timing reference accuracy, and GPS receiver acquisition settings. The results show that satellite signal strength and initialization error are the most important factors in achieving acceptable TTFM results and can indicate the best receiver settings.
Published in:	Proceedings of the 2002 National Technical Meeting of The Institute of Navigation January 28 - 30, 2002 The Catamaran Resort Hotel San Diego, CA
Pages:	254 - 264
Cite this article:	Behre, Charles, Ornedo, Renato, Rogeness, Gaylord, Moore, Todd, "Satellite Acquisition for a Strike Missile Under Jamming and Time Initialization Constraints," Proceedings of the 2002 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2002, pp. 254-264.
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