Positioning Performance Analysis of Loran Stations in Western China

Long range navigation (Loran) system is an effective backup and supplement of the Global Navigation Satellite System (GNSS). Loran signal propagates along the earth surface in the form of ground wave. With the increase of propagation distance, the ground wave signal will be affected by the ground electrical parameters, causing a certain additional propagation delay. The signal field strength will gradually weaken via distance. In order to analyze the positioning performance of Loran stations in western China, the relationship between secondary factor and distance in different media types is analyzed theoretically, and the variation of field strength with distance is calculated based on the propagation law of electromagnetic wave. According to the minimum performance standard of Loran receiver, the coverage area and positioning range of the western station are analyzed, and the Geometric Dilution of Precision (GDOP) in the positioning area are calculated. The results show that GDOP of most areas in the positioning range are less than 6. In the calculation area, the positioning error of western stations is simulated. The analysis results show that the geometric layout of western stations is reasonable. However, due to the influence of secondary factor, the positioning errors in latitude and longitude directions are relatively large. Therefore, it is necessary to adopt differential methods to suppress the observation errors to improve the positioning accuracy. In order to expand the positioning area of Loran station, the receiving ability of the receiver needs to be improved.