EUROFIX: definition and current status

Abstract

The existing Loran-C infrastructure may with some minor changes become a very powerful augmentation system for GNSS. By additional modulation of the Loran-C pulses a long-range data channel can be established which enables broadcasting of DGNSS correction data and integrity information to GNSS users. Unlike other DGNSS services Eurofix offers a full navigation back-lip system in case GNSS fails. The applied additional three-level modulation is fully balanced so it has negligible influence on the basic Loran-C positioning accuracy. Since 1989 Delft University has been working on this system called Eurofix. The user may expect DGNSS accuracies of better than 5 meters (95%) over the full coverage area that eventually will cover entire Europe. During normal operational conditions the Loran-C ASF model imperfections stored in the receiver are continuously calibrated by the found precise DGNSS positions thereby introducing an efficient zero-baseline DLoran-C system. So, during periods of poor GNSS reception, highly calibrated Loran-C may take over. This way, Eurofix offers the user highly accurate DGNSS data, as well as external GNSS integrity and improved radionavigation availability. The German DOT in close cooperation with NELS started experimental Eurofix transmissions in February 1997. The continuing successful DGPS performance tested in France, Germany, the Netherlands and Switzerland mane NELS decide to extent Eurofix in 1998 to another three Loran-C stations at Lessay (France), Voerlandet (South Norway) and Bo (north Norway). This will make Eurofix available in all NELS countries ranging from the North Cape down to the Pyreneans. These four stations also allow extensive testing of the Regional Area Augmentation System capability of Eurofix. As RAAS may significantly reduce temporal and spatial correction data decorrelation further improvements of the system are anticipated.