T. Kondo, N. Kurihara, Y. Koyama, J. Nakajima, R. Ichikawa, E. Kawai, M. 
Sekido, T. Yoshino, J. Amagai, T. Sebata, M. Furuya, Y. Takahashi, H. Kiuchi, 
A. Kaneko
Recent VLBI activities at the Communications Research Laboratory, Japan
 
                   ABSTRACT
 
 
Communications Research Laboratory (CRL) has led the development of VLBI
technique in Japan and is keeping high activities in both observations and
technical developments.  CRL has promoted Key Stone Project (KSP) dedicated to
monitoring the crustal deformation around the Tokyo metropolitan area using the
space geodetic technique such as VLBI and SLR.  In the KSP, real-time VLBI
technique was developed and it has been applied to form a large big radio
telescope connected by a high speed communications link.  As for the next
generation VLBI terminal, the Giga-bit VLBI system consisting of a high speed
sampler (1Gsps/4ch/2bit) and a high speed digital data recorder (1024 Mbps) has
also been developed.  The first fringes using this system were successfully
observed.  Besides these developments, optical-linked RF interferometer has been
investigated to measure phase delay precisely.  The performance of GPS frequency
reference receiver was tested to evaluate the possibility of its adoption as a
frequency standard in VLBI observations in order to deploy VLBI-like techniques
widely.
 
-----------------------------------------------------------------------
In Proceedings of the 13th Working Meeting on European VLBI for Geodesy
and Astrometry, Viechtach, 1999
 
Keywords: KSP, real-time VLBI, Giga-bit VLBI system, optical-linked RF interferometer, GPS reference receiver