Preliminary study of multichain-based Loran positioning accuracy for a dynamic user in South Korea

The long range navigation (Loran) system is a terrestrial high-power radionavigation system using 100-kHz signals. It can be a complementary positioning, navigation, and timing (PNT) system for maritime users because of its robustness to radio frequency interference, even though its positioning accuracy is low compared to that of GNSS. South Korea has suffered from GPS jamming attacks from the North and decided to deploy a nationwide enhanced Loran (eLoran) system. However, the Korean eLoran project has been delayed several times because of contractual problems and other issues. Therefore, we developed a multichain-based Loran positioning method to improve the current Loran positioning performance, which does not require hardware upgrades of existing Loran transmitters to eLoran capability. We have previously demonstrated an approximately 15-m (95%) accuracy for a static user by applying our multichain-based Loran positioning algorithm and the time-difference-of-arrival (TDOA)-based temporal additional secondary factor (ASF) correction method when a user was approximately 12 km from a differential correction station. In this study, we examine the improved Loran positioning performance for a dynamic user based on the multichain algorithm and the existing Loran infrastructure in Northeast Asia. TDOA-based ASF maps, which are different from conventional time-of-arrival (TOA)-based ASF maps for eLoran, are generated to compensate for spatial ASF errors for the dynamic user.