Assessment of Time Transfer Performance between TWSTFT and GPS Carrier Phase at KRISS

By the use of Global Position System (GPS) carrier phase and two-way satellite time and frequency transfer (TWSTFT) measurements, a set of time comparisons has recently been conducted world-wide. Those time transfer methods have been conducted between Korea Research Institute of Standards and Science (KRISS) and other National Metrology Institutes (NMIs). The GPS time transfer can be routinely conducted at KRISS and the TWSTFTs are utilized as well The GPS all-in-view time transfer method is currently officially utilized by BIPM for the computation of International Atomic Time (TAI), while time transfer by carrier phase method still needs more researches. Since the precision that carrier phase measurements can provide is much higher than that of P code, some effects that could be safely ignored in P-code time transfer should be accounted for in order to fully utilize the precision of the carrier phase measurements. We present the comparison results between TWSTFT and GPS time transfer using carrier phase and P3 code for several months.