New Loran Capabilities Enhance Performance of Hybridized GPS/Loran Receivers

G. Linn Roth and Paul W. Schick

Abstract:	The United States is in the midst of a major re-evaluation of its GPS policy, and it is clear sole-means GPS will not be part of that policy. As a result, radionavigation systems previously scheduled for termination, such as Loran, will continue operations for at least another decade. Perhaps because of the earlier rush to a sole-means GPS judgement, the performance of the Loran system has not been objectively evaluated for several years. On-going development has led to a new generation of Loran receivers that conclusively demonstrate Loran’s capabilities are much better than previously appreciated. New all-in-view Loran receivers typically track 20-30 transmitters in North America and provide performance enhancements analogous to the change from sequencing to all-in-view GPS receivers. It is also clear Loran receiver technology can make yet another significant performance advance, and the limiting component of current Loran system performance is the transmitters, which require synchronization to UTC and upgrades to monitoring and control electronics. New developments such as Eurofix, which could distribute DGPS corrections over the entire US and substantial oceanic areas in an extremely cost-effective manner, also enhance Loran system capabilities significantly. These new Loran capabilities mean Loran is an ideal complement to GPS in the new, non-sole-means situation, and hybridized Loran/GPS can offer performance neither system can provide alone. For example, all-in-view Loran receivers mean UTC synchronized Loran transmitters can be used as GPS pseudolites and improve GPS availability by at least two orders of magnitude. Eurofix could provide WAAS-like capabilities at minimal cost and better, more expansive DGPS coverage than even a fully deployed NDGPS system. Perhaps most importantly, combined GPS/Loran systems would provide true radionavigation redundancy and safety for all users, including telecommunication and other critical infrastructure groups. Finally, US support of combined GPS/Loran receivers will enhance international acceptance of GPS by mitigating many contentious issues such as continuous availability, and liability, and thereby promote global use of GPS. This paper will document the evolution of new Loran capabilities and the potential for hybridized GPS/Loran receivers with performance far exceeding either alone.
Published in:	Proceedings of the 1999 National Technical Meeting of The Institute of Navigation January 25 - 27, 1999 Catamaran Resort Hotel San Diego, CA
Pages:	425 - 433
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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