GPS-IMU-Loran Integration for Airborne Applications

David A. Anderson and James H. Doty

Abstract:	Precision navigation is required for many modern avionics systems. Under ideal conditions, GPS is capable of providing accurate and reliable position information at a low cost. However, due to low signal power, GPS can easily be disrupted by both intentional and unintentional interference. The 2001 Department of Transportation Volpe Center’s GPS Vulnerability Study highlighted the vulnerabilities of GPS and the need for a back-up to GPS. Precision Inertial Navigation Systems (INS) can be used to coast through GPS outages; however, a lower cost solution is desirable. Loran has been proposed as a candidate for a back-up to GPS. By itself, Loran cannot provide the same performance as GPS, which is required for some applications. However, Loran performance can be improved since Loran measurement biases can be observed, estimated, and corrected. In addition, Loran positioning noise can be greatly reduced by integration with a low-cost inertial measurement unit (IMU). We will show how the receiver autonomous integrity monitoring (RAIM) techniques commonly used in GPS avionics receivers can be adapted to provide position integrity for the integrated solution. The implications of using time difference of arrival (TDOA) measurements in conjunction with RAIM will be discussed. The design of a GPS-IMU-Loran integration system and flight test results will also be discussed.
Published in:	Proceedings of the 2004 National Technical Meeting of The Institute of Navigation January 26 - 28, 2004 The Catamaran Resort Hotel San Diego, CA
Pages:	1077 - 1086
Cite this article:	Anderson, David A., Doty, James H., "GPS-IMU-Loran Integration for Airborne Applications," Proceedings of the 2004 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2004, pp. 1077-1086.
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