Comparison with GPS Time Transfer and VLBI Time Transfer

To compare the results with Global Po- sitioning System (GPS) Time Transfer and Very Long Baseline Interferometry (VLBI) Time Trans- fer, we carried out the geodetic VLBI experi- ments for four times. The averaged formal error (1σ) of the clock offsets that were estimated every one hour in the geodetic VLBI analysis procedure (CALC/SOLVE), was 33 picoseconds. Especially, in the case of using K5/VSSP32 system, the aver- aged formal error was 29 picoseconds. The results of the VLBI time transfer were very consistent with the results of the GPS time transfer. The differ- ence of both results was about ±500 picoseconds. In term of frequency stability, the Allan deviation showed that VLBI time transfer is more stable than GPS time transfer between 2000 seconds to 60000 seconds (uncertainty of under 3 × 10−14)