Development of Broadband VLBI System and Report of Experiments for Geodesy and Frequency Comparison

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  • Sekido Mamoru
    National Institute of Information and Communications Technology, Kashima Space Technology Center
  • Takefuji Kazuhiro
    National Institute of Information and Communications Technology, Kashima Space Technology Center
  • Ujihara Hideki
    National Institute of Information and Communications Technology, Kashima Space Technology Center
  • Kondo Tetsuro
    National Institute of Information and Communications Technology, Kashima Space Technology Center
  • Tsutsumi Masanori
    National Institute of Information and Communications Technology, Kashima Space Technology Center
  • Miyauchi Yuka
    National Institute of Information and Communications Technology, Kashima Space Technology Center
  • Kawai Eiji
    National Institute of Information and Communications Technology, Kashima Space Technology Center
  • Takiguchi Hiroshi
    National Institute of Information and Communications Technology, Headquarter
  • Hasegawa Shingo
    National Institute of Information and Communications Technology, Kashima Space Technology Center
  • Ichikawa Ryuichi
    National Institute of Information and Communications Technology, Headquarter
  • Koyama Yasuhiro
    National Institute of Information and Communications Technology, Headquarter
  • Hanado Yuko
    National Institute of Information and Communications Technology, Headquarter
  • Watabe Kennichi
    National Institute of Advanced Industrial Science and Technology, National Metrology Institute of Japan
  • Suzuyama Tomonari
    National Institute of Advanced Industrial Science and Technology, National Metrology Institute of Japan
  • Kawabata Ryoji
    The Geospatial Information Authority of Japan
  • Fukuzaki Yoshihiro
    The Geospatial Information Authority of Japan
  • Ishimoto Masayohi
    The Geospatial Information Authority of Japan
  • Wakasugi Takahiro
    The Geospatial Information Authority of Japan
  • Umei Michiko
    The Geospatial Information Authority of Japan
  • Toyoda Tomoo
    The Geospatial Information Authority of Japan
  • Komuro Jun'ichi
    National Institute of Information and Communications Technology, Headquarter
  • Terada Kenjiro
    National Institute of Information and Communications Technology, Headquarter
  • Namba Kunitaka
    National Institute of Information and Communications Technology, Headquarter
  • Takahashi Rumi
    National Institute of Information and Communications Technology, Headquarter
  • Okamoto Yoshihiro
    National Institute of Information and Communications Technology, Headquarter
  • Aoki Tetsuro
    National Institute of Information and Communications Technology, Headquarter
  • Ikeda Takatoshi
    National Institute of Information and Communications Technology, Headquarter

Bibliographic Information

Other Title
  • 広帯域VLBIシステムの開発と測地・周波数比較実験の報告
  • コウタイイキ VLBI システム ノ カイハツ ト ソクチ ・ シュウハスウ ヒカク ジッケン ノ ホウコク

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Abstract

<p>We have developed a new broadband VLBI system GALA-V for distant frequency comparison project. The GALA-V broadband VLBI observation system is designed to be compatible with the concept of the next generation geodetic VLBI system: VGOS (VLBI Global Observing System). The GALA-V system contains advanced technologies, such as (1) unique broadband feed, which enables upgrading standard Cassegrain telescope to broadband radio telescope, (2) RF direct sampling and broadband bandwidth synthesis. We have originally developed broadband feed (NINJA Feed), which has been installed to Kashima 34-m antenna, and we have successfully realized high-gain large diameter broadband antenna with Cassegrain optics. The combination use of RF-Direct sampling technique and broadband bandwidth synthesis have achieved stable high precision group delay measurement. The GALA-V system demonstrated sub-pico second precision delay measurement by one second of VLBI observation of extragalactic radio source with Kashima 34 m - Ishioka 13 m baseline. Our project is targeting to make precision frequency comparison and geodetic measurements with transportable small diameter antennas. We have conducted a series of broadband VLBI experiments between two small telescopes installed at NICT (Tokyo) and NMIJ (Tsukuba) for measurement of clock difference between UTC (NICT) and UTC (NMIJ). These experiments demonstrated that broadband observation enables one pico-second or better delay precision measurement even by using small diameter radio telescopes. Weighted RMS of post-fit delay residual of a pair of 1.6 m & 2.4 m antennas was about 14 psec in the session on 25th Nov., which is the same level with the best precision current geodetic VLBI observation with large diameter antennas. The experiment results suggest that analysis errors of broadband VLBI are no more limited by delay measurement precision, but totally dominated by atmospheric delay uncertainty.</p>

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