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Zusammenfassung:
Very Long Baseline Interferometry (VLBI) is an essential tool for building a multi-technique combined Terrestrial Reference Frame (TRF). Optical surveying of the reference point of a VLBI telescope is a crucial method for obtaining high-precision local-tie vectors and constructing multi-technology combined TRFs. Since the reference point of a VLBI telescope is not visible, the telescope's reference point must be determined by fitting the trajectory of target points that track the VLBI telescope. Unmanned GNSS methods have emerged since 2009, and various monitoring experiments with GNSS receiving antennas as targets have been conducted. Although this method can achieve continuous monitoring, it is limited by the single-point positioning accuracy and multipath effects of GNSS antennas, leading to a significant proportion of GNSS observations being compromised. High-precision laser scanners can obtain high-precision target points, but their observation error correction effect still needs further verification as they cannot be leveled. The most significant problem with using high-precision prisms for reference point determination is the system errors in ranging distances and angle measurements caused by the prism's incident angle, such as angles > 20 degrees.
Based on the geometric relationship between the prisms, telescope, and monitoring instruments, we have designed an unmanned monitoring system with a self-driven prism. The system enables a face-to-face alignment between the surface of the prism and the surface of the monitoring instrument lens of the total station, which can not only perform high-precision determination of the reference point of VLBI telescopes but also calibrate the continuous monitoring trajectory of GNSS targets.
