Citation
Abstract
An advanced water vapor radiometer (WVR), currently under development in the DSN Technology Program, will serve as the critical remote sensing instrument in the troposphere calibration subsystem required by the Cassini radio science experiments. The ability of WVRs to calibrate changes in tropospheric delay was demonstrated during very long baseline interferometry (VLBI) observations on the 21-km baseline between DSS 13 and DSS 15 at Goldstone, California. WVR measurements reduced the observed VLBI post-fit delay residuals over a 13-h period from 43.8 ps to 16.9 ps, a factor of …2.5. When applied to shorter time intervals, an …50-percent reduction in the Allan standard deviation of the site-differenced residual delay on 100- to 700-s time scales was achieved during conditions of high tropospheric activity. Thermal WVR noise precluded calibration of delay fluctuations on shorter time scales and during quiet tropospheric conditions.
Details
- Volume
- 42-126
- Published
- August 15, 1996
- Pages
- 1–8
- File Size
- 304.8 KB