Abstract
We are developing a compact VLBI (Very Long Baseline Interferometry) system with 1.6 m diameter aperture dish in order to provide reference baseline lengths for calibration. The reference baselines are used to validate surveying instruments such as GPS (Global Positioning System) and EDM (Electro-Optical Distance Measurement) and maintained by the Geospatial Information Authority (GSI) of Japan. The compact VLBI system is designed to be assembled with muscle power simply in order to perform short-term (about one week) measurements at several reference baselines in Japan islands. First, we have evaluated a front-end system with a wideband quad-ridged horn antenna by installing it on the 2.4 m diameter antenna at Kashima as a feasibility study. We have successfully carried out five geodetic VLBI experiments using it during September 2006 to July 2008. In addition we have concluded the new analysis concept to obtain indirectly the group delays on the baseline between two compact dishes is available. Next, we have carried out the VLBI experiments on the Kashima-Tsukuba baseline (about 54 km) using the two compact VLBI system during December 2009 to October 2010. The averaged baseline length and repeatability of the experiments is 54184875.1 ±2.5 mm.
