WANG Na1, 2, SU Jian-feng1, LI Rui-min1, 2

(1. National Time Service Center, Chinese Academy of Sciences, Xi′an 710600, China;

 2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China)

Abstract:Accurate calculation of field-strength and delay of ground-waves is a key technology in timing via BPL and Loran-C. In this paper the calculation of field-strength and second phase factor for low-frequency range and any distance is realized by using VC++ object-oriented and visualization programming. The Microsoft Windows graphical user-interface makes engineering persons to operate easily, and this interface is more understandable and more practical. The comparisons show that the calculation results coincide with available data very well.