Airborne Testing of GPS+GLONASS Positioning Sensor Against A Proven Flight Test Truth Source

James G. Murphy, William V. Cottrell

Abstract:	As the Russian Global Navigation Satellite System (GLONASS) matures, the potential benefits to airborne navigation and positioning operations have become increasingly obvious. With the continuing degradation of the GPS signals by the US Department of Defense policy of Selective Availability (SA), the accuracy of the GLONASS signal is being leveraged by many organizations in the aviation industry. Designers of Flight Management Systems (FMS), GNSS Landing Systems (GLS) as well as manufacturers of other types of avionics and a myriad of Airborne Mapping firms have already laid plans to take advantage of the capabilities of positioning sensors which combine GPS and GLONASS. However, the flight testing of this new combined positioning technology poses some technical and logistical problems. There is no shortage of terrestrial test data for GPS and GPS+GLONASS. There have also been many well documented experiments undertaken in the airborne environment for GPS. But in order to prove the airborne capabilities of combining GPS and GLONASS, it must be flight tested against proven and reliable Time, Space, Position Information (TSPI) equipment. Currently there are a handful of FAA endorsed TSPI systems; Laser Tracker and Dual-Frequency GPS are the two most widely used. The focus of this test was to determine the true airborne accuracy of combined GPS and GLONASS technology. Dual-frequency GPS best lends itself to this testing due to several inherent logistical limitations of Laser Tracking. The GPS+GLONASS technology was flown against an FAA endorsed dual-frequency GPS receiver. The dual-frequency GPS data served as the truth source data; the GPS+GLONASS data was measured against the truth source data. The test aircraft was a twin-engine Aero Commander aircraft outfitted to serve as a photogrammetry platform (which included the installation of an “certified” dual-frequency GPS receiver and high-gain antenna). Several modes of flight were studied: enroute and terminal area (primarily benign dynamics), approach (moderate dynamics), and “unusual attitudes” (moderate to high-dynamics).
Published in:	Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997) September 16 - 19, 1997 Kansas City, MO
Pages:	1047 - 1054
Cite this article:	Murphy, James G., Cottrell, William V., "Airborne Testing of GPS+GLONASS Positioning Sensor Against A Proven Flight Test Truth Source," Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997), Kansas City, MO, September 1997, pp. 1047-1054.
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