Abstract
In this paper we compare the PTB-TL time transfer link data of TWSTFT and GPS carrier phase solutions. We investigated in detail the double difference between the time transfer data of TWSTFT and GPS IGSC/TAIPPP. Our results show the PTB-TL link has a conspicuously diurnal effect. The periodicity is almost exact 1 day and the peak-to-peak amplitude is about 1-1.5 ns. We also found a phase drift which is about 5 ns between TWSTFT and GPS data during a period of 130 days.