Traceability, stability and use of the Kyviskes calibration baseline – the first 10 years

Abstract

The Kyviškės Calibration Baseline was established by the Institute of Geodesy of the Vilnius Gediminas Technical University (VGTU) in 1996 for calibration of electronic distance measurement (EDM) instruments. The length of the 6-pillar baseline is 1 320 m, and a 7th pillar, established in 2000, extends it to a triangle-shaped test field. The Finnish Geodetic Institute, together with the Institute of Geodesy of VGTU, is measuring the baseline in 5– 6 years cycles with high precision instruments. Calibration results (lengths and uncertainties) of the three first measurements in 1997, 2001 and 2007 are presented. As an essential part of a metrological work, the traceability chain and measurement methods are described as well. The traceability chain from the definition of the metre to baseline lengths consists of several stages: absolute and relative measurements of quartz gauges, standard baseline measurements using white-light interferometry, projection measurements enabling calibration of transfer standards, and finally, calibration of the calibration baseline itself. After all this, 0.2 mm to 1.2 mm total uncertainties have been repeatedly obtained for the lengths of the pillar intervals at Kyviškės. Furthermore, the three results are compatible within the uncertainty limits, showing the baseline and test field very stable. In addition to testing and calibration of EDM instruments, Kyviškės is suitable for testing of total stations and GNSS measurement equipment.