Preliminary study of the re-radiation effect of Loran signal to improve the positioning accuracy

South Korea plans to implement the test bed of the eLoran system in the West Sea and it aims to provide approximately 20 m of positioning accuracy in this area. In order to achieve the desired positioning performance, the Additional Secondary Factor (ASF), which is the major error of the Loran system, needs to be precisely corrected. However, when a service provider surveys spatial ASF to produce an ASF map, calculated spatial ASF value varies depending on the direction of the vehicle equipped with Loran antenna. In this paper, we modeled and removed the re-radiation effect caused by the surrounding structures and verified its performance. Using the GPS / eLoran integrated navigation system developed by KRISO, we verify the performance of proposed algorithm in the West Sea of South Korea. Because we don't have any eLoran transmitter in Northeast Asia not yet, we used multichain-based Loran positioning algorithm and TDOA-based ASF correction method.