Global Transmission Services 2
Global Transmission Services 2 (GTS-2) is an experiment on the ISS on time synchronization.
The time signals from GTS can be received every 90 minutes on earth when flying over the space station for 5 to 10 minutes. GTS transmits on the frequencies 400.1 MHz ( UHF ) and 1.428 GHz ( L-band ). The GTS clock is quartz stabilized. But since it is synchronized with atomic clocks on earth during almost every revolution, it reaches a relative deviation of 10 −13 .
One advantage of GTS compared to the time signal from GPS is the low transmission frequency in the lower UHF range, which enables simple clock receivers even in buildings. In contrast to long-wave transmitters such as DCF77 , which terrestrially broadcasts the official time in Germany, GTS can be received worldwide and has a higher data rate for additional information.