Development of real-time diagnostic system for VLBI using public communication lines

In this paper, a real-time diagnostic system fur VLBI (Very Long Baseline Interferometer) facilities via public communication lines is proposed, and experimental results to check its diagnostic performance are described with a prototype model. In the system, narrow-band radio waves such as beacons of geostationary satellites or emission from strong cosmic maser sources are used as test input signals, which make it possible to reduce the signal sampling rate and to transmit sampled data via public communication lines. Thus, diagnostic results can be obtained in real time. The prototype model was connected to the 6-m radio telescope at the Kagoshima VLBI station and the 10-m radio telescope at the Mizusawa VLBI station, and a test operation was conducted using beacon waves of satellites. It was found that the correlation results of the data transmitted in real time coincide with those obtained by the conventional procedure for VLBI, confirming the effectiveness of the system. (C) 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(6): 1-9, 2001.