Assessing the Limits of eLoran Positioning Accuracy

Enhanced Loran (eLoran) is the latest in the longstanding and proven series of low frequency, LOng-RAnge Navigation systems. eLoran evolved from Loran-C in response to the 2001 Volpe Report on GPS vulnerability. The next generation of the Loran systems, eLoran, improves upon Loran-C through enhancements in equipment, transmitted signal, and operating procedures. The improvements allow eLoran to provide better performance and additional services when compared to Loran-C, and enable eLoran to serve as a backup to satellite navigation in many important applications. The Czech Technical University in Prague (CTU) participates in the eLoran research activities coordinated by the General Lighthouse Authorities of the United Kingdom and Ireland (GLAs). In our work we have focused on questions that arise when considering introducing new eLoran stations into an existing network. In particular, this paper explores the issue of CrossRate Interference (CRI) among eLoran transmissions and possible ways of its mitigation at the receiver end. An eLoran receiver performance model is presented and validated using an experimental eLoran signal simulator developed by a joint effort of CTU and GLAs. The resulting model is used to evaluate the achievable positioning accuracy of eLoran over the British Isles.