Performance Evaluation of eLoran Spatial ASF Corrections Based on Measured ASF Map

This paper analyzes the effectiveness of spatial ASF correction methods in the Korean eLoran system using measured ASF maps. Three correction scenarios were evaluated under identical simulation settings: no correction (S0), local correction using true ASF values (S1), and wide-area correction using a single reference station value (S2). Simulation results show that S1 consistently achieved the lowest positioning errors, while S0 exhibited the largest errors with extensive high-error regions. S2 provided limited improvements near the reference station but degraded with increasing distance and ASF spatial gradients. The findings highlight that local ASF correction significantly improves eLoran positioning performance, whereas wide-area correction has only localized benefits.