Long-range Loran-C ground-wave propagation prediction based on adaptive moving window finite-difference time-domain method with compute unified device architecture parallel computing techniques

Modelling long-range Loran-C signal propagation numerically is challenging because of its extremely high computational cost. Other analytical/semi-analytical methods are not accurate enough because of unavoidable approximations. In this study, the authors put forward a solution using the adaptive moving window finite-difference time-domain (FDTD) method to compute unified device architecture parallel computing techniques. The moving velocity of the window is dependent upon the wave speed adaptively. To achieve the adaptive moving window technique, the original Loran-C signal is truncated first. A further method employed to extract the electric field amplitude and phase is proposed. The electric field amplitude and phase data of each mesh in the computational space are synchronously obtained from the spatial domain as the FDTD updates, without additional storage cost and post processing in the time domain. With all these efforts, a 400 km propagation path was simulated successfully within 22 min. Measurement results between Jinxian and Shangrao in Jiangxi Province, China were taken to validate the numerical approach.