Analysis of Delay Variations of the Loran-C Across Different Atmospheric Environments

The Loran-C signal propagates through various atmospheric environments, and the speed of the electromagnetic signal changes as it moves through different media. This study aims to analyze the variations in the time delay of the Loran-C signal resulting from its passage through distinct atmospheric conditions. This study simulates different atmospheric environments by varying ground conductivity and corresponding atmospheric refractive indices. The propagation of the Loran-C signal through these varied conditions is modeled using a time-domain finite difference method within a two-dimensional coordinate system. The results indicate that, in the atmospheric environment, the ground conductivity has the greatest impact on the secondary delay of Loran-C signals, on the order of microseconds, whereas the effect of atmospheric refraction index is on the order of nanoseconds. The secondary delay of Loran-C signals decrease monotonically with increasing conductivity of the atmospheric environment. When Loran-C signals traverse different atmospheric conditions, propagation delay may experience abnormal changes of tens of nanoseconds. These variations arise from the inconsistency between the signal envelope and waveform propagation speeds.