Title: Very Long Baseline Interferometry for centimeter accuracy geodetic measurements
Abstract: Very Long Baseline Interferometry (VLBI) is one of the most promising of the new techniques for very accurate measurements (a few centimeters) of the distance between widely separated points on the earth, and for precise measurements of variations in Universal Time (UT.l) and polar motion. VLBI experiments conducted in 1972 and 1973 with radio telescopes 3900 km apart yielded values for the baseline length with a weighted root-mean-square spread about the weighted mean of 12 cm. The UT.1 and polar motion (x-component) variations determined from these measurements were comparable to BIH values. The major error source in these VLBI measurements in the calibration of the delay contributions of the neutral atmosphere and ionosphere. We plan to improve the accuracy to the 5-cm level by:
1.
(1) the addition of simultaneous measurements of atmospheric water vapor with microwave radiometers boresighted with the VLBI antennas;
2.
(2) simultaneous VLBI measurements at 2.3 and 8.4 GHz for calibration of the io nsphere;
3.
(3) using a new wideband data acquisition system for improving the signal/noise ratio and calibration of residual instrumental biases; and
4.
(4) using improved models for known geophysical effects including earth tides, diurnal polar motion, etc.
The first application planned for the 5-cm VLBI is the measurement of the distance and motion of Hawaii relative to stations on the North American Plate in California, Alaska, and Massachusetts.
Publication Year: 1975
Publication Date: 1975-12-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 12
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