Prediction of Ground Wave Propagation Delays in Terrestrial Radio Navigation Systems Based on Soil Texture Maps

Terrestrial radionavigation systems, in the lower frequency bands, like eLoran and the upcoming medium frequency R-Mode, are facing the challenge of mitigating ground wave propagation delays to achieve the desired level of accuracy. The prediction requires detailed information about the electrical properties of the ground in the area of interest which can be obtained from the ITU-R P.832. In this paper, we propose a new method to calculate the electrical ground conductivity and permittivity based on soil texture maps. The proposed method allows the computation of Atmospheric and Ground wave Delay Factor (AGDF) maps that provide an improved accuracy and can be adjusted with respect to temperature, soil water content and water salinity. To showcase the performance of the model, we implemented the method for a selected area near the city of Berlin in Germany and evaluated the accuracy in comparison to predictions based on ITU-R P.832 during a measurement campaign. The results show that the new method yields more accurate prediction results.