Recent achievements in very long baseline interferometry.

The Communications Research Laboratory has a long history, more than twenty years, of research and developments devoted to Very Long Baseline Interferometry. Recently, a compact observation network which consists of multiple space geodetic techniques has been established under the Key Stone Project and many technical innovations have been made. The measurement precision and the automated features of the system are two remarkable features of the system. And the four observation sites of the Key Stone Project provide valuable information that can be combined with the results of other space geodetic techniques to construct a global terrestrial reference frame. A possibility to shorten the delay to obtain earth's orientation parameters after an experiment has also been demonstrated. This paper will review these new achievements. (