Study on ionospheric delay correction in GPS signal

When the GPS CV method is used to compare long distant clocks, the ionospheric delay of the received GPS signal can lead to significant errors, and therefore, which need to be measured or corrected. This paper presents three different methods used to calculate the ionospheric delay in GPS signal. By analyzing the precision of three GPS CV corrected results between National Institute of Information and Communications Technology and National Time Service Center, Chinese Academy of Science, three ionospheric delay computing methods are compared. And the results show the precision of GPS CV time transfer, in which the ionospheric delay is corrected by using the double-frequency measurement. And 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.