A demonstration of a transportable radio interferometric surveying system with 3-cm accuracy on a 307-m base line

A precision geodetic measurement system (Aries for Astronomical Radio Interferometric Earth Surveying) based on the technique of very long base line interferometry has been designed and implemented through the use of a 9-m transportable antenna and the NASA 64-m antenna of the Deep Space Communications Complex at Goldstone, California. A series of experiments designed to demonstrate the inherent accuracy of a transportable interferometer was performed on a 307-m base line during the period from December 1973 to June 1974. This short base line was chosen in order to obtain a comparison with a conventional survey with a few-centimeter accuracy and to minimize Aries errors due to transmission media effects, source locations, and earth orientation parameters. The base line vector derived from a weighted average of the measurements, representing approximately 24 h of data, possessed a formal uncertainty of about 3 cm in all components. This average interferometry base line vector was in good agreement with the conventional survey vector within the statistical range allowed by the combined uncertainties (3–4 cm) of the two techniques.