ALBERT

Description: International reference frames are cornerstones for all metrological applications related to Earth sciences covering global change research, global deformation, and mass transport. Over the last two decades, the precision of underlying measurements on which the reference frame is based improved to a millimeter level. However, the overall achieved accuracy remains at centimeter-level errors. In this contribution, we will introduce a promising approach examining imperceptible error sources which influence all types of measurement equipment and which are not captured by any calibration. To make them visible, combinations of different kinds of techniques are needed. The recently established DFG funded research unit “Clock Metrology” introduces the new measurement constraint based on accurate optical clocks to demonstrate the direct measurement of a physical height difference between the Geodetic Observatory Wettzell and the Physikalisch-Technische Bundesanstalt based on optical time transfer. The investigation of systematic errors is based on the introduction of a new timing tie into a measurement and analysis process, guaranteed by the preservation of clock coherence used for systems calibration. Within this research unit, we will develop a new calibration technique that expands local coherence to the measurement process of satellite positioning. We will achieve this by transmitting an artificial Galileo signal preciously synchronized to a common clock.