Abstract:

To accurately determine the rotation center of SLR (Satellite Laser Ranging) and VLBI (Very Long Baseline Interferometry) is a key problem in surveying co-located tie vector. This paper develops an approach of directly solving the collocated tie vector by using two kinds of constraints between SLR and VLBI’s antenna rotation center and observation marks. The first constraint is that the mark forms a planar circle when it rotates along with its rotation axis, which can be modeled as the intersection of a plane and a sphere. The second constraint is that the rotation center lies in the same plumb line with the rotation center of vertical axis, and in the same plane with the rotation center of horizontal axis. The corresponding condition equations are established according to the two kinds of constraints. The tie vector and its covariance matrix are directly resolved by using the observations of the mark points. The space differences baseline are solved based on the direct approach using measured data of seven GNSS (Global Navigation Satellite System) and SLR or VLBI co-location. The results show that the difference is better than 1mm compared with two step solutions.

Key words: GNSS, SLR, VLBI, differences baseline, space coordinate differences surveying