Flight Testing of a Pseudolite Navigation System on a UAV

John H.R. Amt and John F. Raquet

Abstract:	Due to an increasing reliance on navigation as an assumed infrastructure in many systems, there is an increasing need to develop non-GNSS based navigation systems that work in situations where GNSS systems are not available. One good example is a flight reference system, which is used to test navigation systems in a variety of environments. If a flight reference system’s accuracy is fundamentally dependent on precision DGPS (as is often the case), then that system will not be appropriate for conducting testing in GPS-denied environments. One promising approach to solve this problem is the use of non-GNSS navigation beacons (sometimes referred to as pseudolites). This paper describes flight testing of a new pseudolite navigation system built by Locata that operates in the 2.4 GHz ISM band. Up to now, the Locata system has been used almost exclusively on the ground, where it has demonstrated positioning accuracy at the 3-5 cm level compared to kinematic carrier-phase DGPS. This paper describes a series of UAV flight tests of the Locata system conducted at the Advanced Navigation Technology (ANT) center at the Air Force Institute of Technology. Previous research has developed methods to characterize geometry effects for pseudolite applications as well as methods, such as primary component analysis, that can be used to mitigate situations where there is poor measurement geometry. The flight test is described in detail, including the hardware configuration of the ANT Center UAV, which simultaneously flew a Locata receiver, a NovAtel GPS receiver, and a radio datalink system. The results indicate that there is strong agreement between the GPS and Locata solutions when there is good measurement geometry for Locata.
Published in:	Proceedings of the 2007 National Technical Meeting of The Institute of Navigation January 22 - 24, 2007 The Catamaran Resort Hotel San Diego, CA
Pages:	1147 - 1154
Cite this article:	Amt, John H.R., Raquet, John F., "Flight Testing of a Pseudolite Navigation System on a UAV," Proceedings of the 2007 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2007, pp. 1147-1154.
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