Performance Analysis of Integrated GPS/INS Guidance for Air-to-Ground Weapons in a Jamming Environment

Kenneth M. Kessler, Fred G. Karkalik, Jerry Sun, John D. Brading

Abstract:	This paper addresses several findings of a recent study undertaken by Systems Control Technology, Inc. and supported by Mayflower Communications Company. A phase 1 study [l], evaluated candidate low-cost integrated Global Positioning System and Inertial Navigation System (GPS/INS) configurations for guided standoff weapons. The focus was directed toward three low-cost GPS/INS concepts. The first uses a receiver on-board the vehicle and is an autonomous GPS/INS guided weapon which is initialized and launched from a delivery aircraft. The second and third configurations use a GPS translator on-board the weapon to re-transmit the GPS signals to a GPS receiver on the aircraft, or to a ground station operating in a differential mode. The Phase 2 effort reported here examines the issues related to integration techniques and EW vulnerability. Only the autonomous configuration was investigated in Phase 2. An analysis was conducted of the jamming vulnerability of various receiver/INS configurations by evaluating the performance degradation in the presence of jamming using two simulations. In the first simulation, actual real-time GPS receiver tracking loop software was used to generate a functional relationship between jammer power level and RMS tracking error, for two configurations. One, an integrated design and the second a "stand-alone" receiver, one navigation without the benefit of aiding obtained from an inertial system. This numerically derived functional model was incorporated in teh second simulation which utilized both covariance propagation equations and measurem,ent "aiding", or updates, to the INS based navigator. The measurement noise used to update the Kalman filter equations directly utilized the functional model obtained from the GPS receiver trackign loop. The covariance simulation was "flown" along a trajectory and used to generate CEPs for various weapon/jammer configurations. The paper is organized as follows: the background section touches on points of general interest and sketches general requirements, integration issues are highlighted next, followed by a simulation section which discusses how the analyses for these studies were conducted. The results are presented next, and the final section contains the conclusions.
Published in:	Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991) September 11 - 13, 1991 Albuquerque, NM
Pages:	139 - 148
Cite this article:	Kessler, Kenneth M., Karkalik, Fred G., Sun, Jerry, Brading, John D., "Performance Analysis of Integrated GPS/INS Guidance for Air-to-Ground Weapons in a Jamming Environment," Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991), Albuquerque, NM, September 1991, pp. 139-148.
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