Marine Radiobeacon DGNSS Service - Predicting Availability and Continuity

Alan Grant, David Last, and Nick Ward

Abstract:	The maritime radiobeacon differential GNSS service in Europe has expanded very rapidly in the last two years. In September 2001, a new frequency plan was brought into effect across the whole of the European Maritime Area (EMA). This has resulted in reduced levels of interference and enhanced coverage. There are now 162 maritime differential beacons positioned so that, as far as possible, all critical coastal locations are served by at least two stations. Recently, maritime administrations agreed specifications for the levels of availability and continuity the service should provide. These values depend on whether the location is oceanic, coastal, a harbour approach, or an inland waterway. However, although there have long been software tools for computing the coverage of radiobeacon differential systems, there has been no such tool that administrations could employ to predict availability or continuity. This paper addresses that shortcoming. It describes a novel approach to these key parameters that takes into account beacon availability figures and combines them with propagation factors including groundwave signal attenuation, interference, and skywave fading at night. We then propose a novel way of assessing availability and continuity, and embody these principles in a computer model. The resulting software tool maps the availability and continuity of the service enjoyed by users. It accommodates both individual beacons and networks of beacons in a way that allows administrations to see whether their systems meet the standards. Availability and continuity maps produced by the new programs are presented in the paper.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	2657 - 2667
Cite this article:	Grant, Alan, Last, David, Ward, Nick, "Marine Radiobeacon DGNSS Service - Predicting Availability and Continuity," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 2657-2667.
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