• Ultra-rapid UT1 measurement by e-VLBI

      Sekido, M; Takiguchi, H; Koyama, Y; Kondo, T; Haas, R; Wagner, J; Ritakari, J; Kurihara, S; Kokado, K (Terra Scientific Pub. Co., 2008)
      The latency of UT1 measurement with Very Long Baseline Interferometry (VLBI) has been greatly reduced by using e-VLBI technology. VLBI observations on the baseline formed by the Kashima 34-m and the Onsala 20-m radio ...
    • VLBI and GPS carrier phase time and frequency transfer

      Takiguchi, H; Koyama, Y; Ichikawa, R; Gotoh, T; Ishii, A; Hobiger, T (National Institute of Information and Communications Technology (NICT), 2010)
      As one of the new frequency transfer technique to compare the next highly stable frequency standards, we proposed the geodetic VLBI technique. We evaluated the ability of VLBI frequency transfer by comparison with GPS ...
    • VLBI measurements for frequency transfer

      Takiguchi, H; Koyama, Y; Ichikawa, R; Gotoh, T; Ishii, A; Hobiger, T; Hosokawa, M (National Institute of Information and Communications Technology (NICT), 2010)
      We carried out the intercomparison experiment between VLBI and GPS to show that VLBI can measure the correct time difference. We produced an artificial delay change by stretching the Coaxial Phase Shifter which was inserted ...
    • VLBI measurements for Frequency Transfer

      Takiguchi, H; Koyama, Y; Ichikawa, R; Gotoh, T; Ishii, A; Hobiger, T; Hosokawa, M (National Institute of Information and Communications Technology (NICT), 2008)
      We compare the frequency transfer precision between VLBI and GPS carrier phase using IVS and IGS observation data in order to confirm the potential of VLBI time and frequency transfer. The results of the VLBI frequency ...
    • VLBI Measurements for Time and Frequency Transfer

      Takiguchi, H; Koyama, Y; Ichikawa, R; Ishii, A; Hobiger, T; Hosokawa, M (Japan Society of Applied Physics (JSAP), 2008)
      原子泉型周波数標準器及び光周波数標準器の開発が世界各国で進められているが,このような 高精度の周波数標準器を比較する新しい時刻比較技術の開発も必要である.宇宙測地技術のひ とつであるVLBI は,遥か彼方の天体から放射される電波を,複数のアンテナで受信し,その 到達時間の差(遅延時間)を精密に計測している.解析では,遅延時間を各種物理パラメータと, 局の位置,速度,大気遅延と共に,基準局に対する観測局のクロックオフセットを未知パラメ ...
    • VLBI measurements for time and frequency transfer (from the EFTF forum, 2008)

      Takiguchi, H; Koyama, Y; Ichikawa, R; Gotoh, T; Ishii, A; Hobiger, T; Hosokawa, M (European Frequency and Time Forum, 2008)
      Modern cold-atom-based frequency standards have already archived the uncertainty of 10-15at a few days. Moreover cold-atom-based optical clocks have the potential to realize the uncertainty of from 10-16 to 10-17 level ...
    • VLBI Measurements for Time and Frequency Transfer (from the JGU meeting, 2008)

      Takiguchi, H; Koyama, Y; Ichikawa, R; Ishii, A; Hobiger, T; Hosokawa, M (Japan Geoscience Union, 2008)
      Modern cold-atom-based frequency standards have already archived the uncertainty of 10−15 at a few days. Moreover coldatom- based optical clocks have the potential to realize the uncertainty of from 10−16 to 10−17 level ...
    • VLBI measurements for time transfer between time and frequency laboratories

      Takiguchi, H; Koyama, Y; Ichikawa, R; Gotoh, T; Ishii, A; Hobiger, T (American Geophysical Union, 2007)
      In the usual geodetic VLBI analysis, clock offsets and their rates of change at participating stations except for the reference station are estimated. The averaged formal error (1σ) of the clock offsets is typically about ...