The Loran-C system employs the spherical hyperbola positioning (SHP) method. However, SHP has three drawbacks in inland regions: first, approximating the Earth’s ellipsoid as a sphere introduces positioning errors; second, hyperbola positioning inherently suffers from a high geometric dilution of precision (GDOP) value; third, it is not easy to simultaneously receive long-wave signals from an entire chain of stations under complex propagation paths, which, to some extent, limits the application and development of the Loran-C system in inland areas. This paper addresses the limitations of the SHP algorithm and introduces the ellipsoidal pseudorange positioning (EPP) method, which eliminates the need to approximate the Earth’s ellipsoid as a sphere. This pseudorange positioning algorithm reduces the GDOP value, enabling navigation and positioning with signals from just three stations, thereby breaking through the restriction of requiring signals from a single chain. Simulation analyses were conducted for various Loran-C chains in China. Due to differences in the geometric layout of the chains, the EPP algorithm improved the positioning coverage area by 129.1% to 284.6% compared to the SHP algorithm. In field test data from the Maoming region of Guangdong Province, China (a typical inland mountainous environment), the EPP algorithm significantly reduced the root mean square error (RMSE), from 417.2 m with the SHP algorithm to 43.1 m, representing an improvement of 89.7%. Both the simulation and experimental results demonstrate that the EPP method effectively addresses errors in Earth ellipsoid modeling, significantly reduces the GDOP, and substantially improves the positioning accuracy and usable area of the Loran-C system in complex inland terrain. This provides more reliable technical support for Loran-C applications in inland navigation, timing, and timing backup.

Conventional Loran‐C is mainly used for low‐altitude users; however, when the Loran‐C signal station or receiving point is at a higher altitude, the ranging error caused by the elevation change cannot be ignored. The traditional groundwave path correction method for high altitude regions idealises the complex groundwave path as a smooth, extensive elliptic line. However, this is a rough and inaccurate correction value for the groundwave path. In this paper, based on the Huygens–Fresnel principle, we analyse the Loran‐C groundwave path, and propose the Groundwave path accumulation (GPA) method, which calculates the complex terrain groundwave transmission paths in segments, to solve the problem of the low accuracy of in the traditional method. With the opening of high‐altitude Loran‐C stations in western China, the algorithm in this paper can improve the accuracy of Loran‐C users' packet positioning to a certain extent in central and western China, Central Asia, and South Asia. The article analyses the correction value of the GPA algorithm to the Loran‐C ground wave transmission distance between two points with elevation, and the ground wave path correction value is 46.918 m in the elevation difference of 2500.000 m and no elevation distance of 414,306.538 m.