Usage of Terrestrial DGPS Services for High Precision Aircraft Applications

Sven Martin

Abstract:	Commercial aviation and general aviation are two of the major users of GPS positioning and navigation. But for safety critical reasons they require high accuracy, availability and reliability of the position information. Hence during the last years wide area augmentation systems like WAAS, EGNOS and MSAS have been developed. Nevertheless they are still under development and will reach operational capability only in a few years. But many airborne applications require a high precision positioning and navigation nowadays. Especially users of special mission aircrafts (e.g. meteorological airdata measurements, airborne gravimetry, airborne photogrammetry, instrumentation flight testing and certification etc.) and helicopters demand a precise positioning. Rescue helicopters use navigation systems to localize accidents or for precision approaches on medical centers. Search and Rescue helicopters (SAR) often operate under non-visual meteorological conditions or during nights. Therefore the pilot needs every additional information he can get about his position. Many countries have already set-up terrestrial DGPS services, which provide different levels of accuracy. Most of these services broadcast correction data in RTCM format. It ranges from RTCM Type 1 messages for code corrections up to RTCM Type 18/19 or 20/21 for RTK carrier-phase corrections. Due to wide area coverage or a huge number of transmitter stations these services can also be used for airborne applications. This paper describes the different terrestrial DGPS services (e.g. FM sub carrier transmission, VHF broadcast, long wave broadcast, Digital Video Broadcast data transmission etc.) which can be used for aircraft applications. Technical aspects of broadcast coverage, availability and accuracy during flights will be addressed. In addition results from flight trials will be presented. A special focus is taken on the usage of a DGPS reference station system for RTK carrier-phase solution.
Published in:	Proceedings of the 2001 National Technical Meeting of The Institute of Navigation January 22 - 24, 2001 Westin Long Beach Hotel Long Beach, CA
Pages:	310 - 318
Cite this article:	Martin, Sven, "Usage of Terrestrial DGPS Services for High Precision Aircraft Applications," Proceedings of the 2001 National Technical Meeting of The Institute of Navigation, Long Beach, CA, January 2001, pp. 310-318.
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