Geometry and gravity related measurement techniques allow for implementation of a European geodetic reference frame. Nowadays, applications of a Global Navigation Satellite Systems (GNSSs) are the dominant technique measure the geometry for continental regions. Direct measurements of the gravity or levelling are techniques related to the gravity field of the Earth. All techniques need to take variation of system Earth into account, if a longer time period or higher accuracy of site locations is in the focus.
Combination of different techniques is not only a validation of one technique against another one, but it also opens new applications, e.g. levelling with GPS GNSS by using known geoids’ information. EUREF supports such practical aspects by the European Vertical Reference Network (EUVN) and EUVN-DA actions. GNSS and levelling measurements refer to discrete points. Developments of remote sensing methods extend the measurement of geodetic reference frame components from points to the surface, e.g. Synthetic Aperture Radar (SAR) measures height changes of the Earth’s surface. The combination of SAR and GNSS is a challenge for the future. A couple of developments, which include to transport GNSS observations in real-time (data streaming) and even to calculate the receiver position in real-time are almost completed. The provision of geodetic reference frames in real-time has an important impact on current practise. The installation of new satellite navigation systems beside GPS and GLONASS, such as Galileo, BeiDou, and QZSS and NavIC, results in autonomous stand-alone solutions and combined multi-GNSS techniques. More satellites for the multi-GNSS scenario are going for deployment in the near future and investigations to understand improvements for geodetic aspects have already started.
This session presents developments, analysis and results of all techniques that are relevant for the establishment of reference frames. Real-time and multi-GNSS developments are of special interest.