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Very Long Baseline Interferometry in the Southern Hemisphere

Published online by Cambridge University Press:  25 April 2016

D. S. Robertson ,
J. S. Gubbay  and
A. T. Legg
D. S. Robertson
Affiliation:
Space Research Group, Department of Supply, Adelaide
J. S. Gubbay
Affiliation:
Space Research Group, Department of Supply, Adelaide
A. T. Legg
Affiliation:
Space Research Group, Department of Supply, Adelaide
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Extract

Phase coherent interferometers with intercontinental baselines became possible because of the development of stable frequency standards. With sufficiently stable frequency standards, no connection is necessary between the two ends of an interferometer. The first VLBI experiments were conducted by a group at the University of Florida who used an intensity interferometer with independent tape recorders for observations of Jupiter. Later, they changed to a coherent system using crystal-controlled oscillators. Since then, several interferometer systems have been developed. A Canadian group developed a system using video tape recorders at each end of the interferometer. They recorded the data in analogue form and managed to bring the two tapes together and to synchronize them to an accuracy of better than a microsecond. After synchronization, the outputs were combined and fringes extracted. Their system has a bandwidth of about 4 MHz. No-one else has attempted a wide-band analogue system.

Type
Invited Papers
Information
Publications of the Astronomical Society of Australia , Volume 2 , Issue 4 , October 1973 , pp. 184 - 187
Copyright
Copyright © Astronomical Society of Australia 1973

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