Li Bian1,2

(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: For more accurately calculating the ionospheric delay in GPS CV (common view) time transfer, which is one of the main factors to affect GPS CV time comparison precision, three different methods of calculating the ionospheric delay are introduced and the different effects of the different calculating methods on the precision of GPS CV comparison are compared and analyzed with the GPS comparison data of NICT(National Institute of Information and Communications Technology) and GPS CV comparison data of NICT-NTSC(National Time Service Center) as some examples. The results show that the precision of GPS CV time transfer in which the ionospheric delay is corrected by using the double-frequency measure and the precision of GPS CV time transfer in which the ionospheric delay is corrected by using the TEC map issued by IGS (International GPS Service) are raised by 30%-40% and 20% -30% respectively compared with the precision of GPS CV time transfer in which the ionospheric delay is corrected by using the ionospheric correction model.

Key words:ionospheric delay; TEC map; GPS CV