Torben Schüler

• Professor at University of the Bundeswehr Munich

The importance of global satellite navigation systems for everyday life and for numerous surveying tasks is well known to every user. Wherever positioning or navigation tasks are involved, GNSS devices for the use of GPS, GLONASS, Galileo or Beidou are used, which provide coordinates in a reference frame of a global geodetic reference system. What...

The Global Geodetic Observing System (GGOS) calls for continues and automated determination of the geometric reference points of space-geodetic techniques such as DORIS, GNSS, SLR and VLBI. Whereas the reference points of DORIS beacons and GNSS antennas can simply be measured by observing well-defined reference markers , the determination of SLR an...

The VLBI (Very Long Baseline Interferometry) technique can provide the full set of parameters needed for the transformation between celestial and terrestrial reference frames with high accuracy. Yet it has some limitations regarding temporal resolution and continuity, and the accuracy of the resulting Earth Orientation Parameters (EOP) varies depen...

The reference point determination of VLBI telescopes is usually done every couple of years and allows for the identification of long-term drifts. In order to detect short-term motions like seasonal deformations, a monitoring system allowing more frequent measurements has to be established. At the Geodetic Observatory Wettzell a quasi-permanent refe...

During the Continuous Very Long Baseline Interferometry (VLBI) Campaign 2017 (CONT17), carried out from 28 November through 12 December 2017, an extensive data set of atmospheric observations was acquired at the Geodetic Observatory Wettzell. In addition to in situ measurements of temperature, humidity, pressure or wind speed at the surface, radios...

Die Kombination von geodätischen Raumtechniken ist essentiell für die Bestimmung eines globalen geodätischen Referenzrahmens sowie von Erdrotationsparametern. Eine direkte Verknüpfung der unterschiedlichen Raumtechniken ist aufgrund der geringen physischen Verknüpfungen nicht ohne Zusatzinformationen sinnvoll möglich. Eine Schlüsselrolle spielen hi...

The present paper provides an overview on the design of a new Satellite Laser Ranging (SLR) system, the Satellite Observing System Wettzell (SOS-W). It pays special attention on the local survey, the determination and monitoring of the ties between the established Wettzell Laser Ranging System (WLRS) and the SOS-W. We also introduce an alternative...

Continuous very long baseline interferometry (VLBI) observations are designed to obtain highly accurate data for detailed studies of high-frequency Earth rotation variations, reference frame stability, and daily to sub-daily site motions. During the CONT-17 campaign that covered a time span of 15 days between 28 November and 12 December 2017, a com...

The Geodetic Observatory Wettzell (GOW), jointly operated by the Federal Agency for Cartography and Geodesy (BKG), Germany and the Technical University of Munich, Germany is equipped with three radio telescopes for Very Long Baseline Interferometry (VLBI). Correlation capability is primarily designed for relative positioning of the three Wettzell r...

Continuous Very Long Baseline Interferometry (VLBI) observations are designed to obtain highly accurate data for detailed studies of high frequency Earth rotation variations, reference frame stability and daily to sub-daily site motions. During the CONT-17 campaign that covered a time span of 15 days between Nov. 28 and Dec. 12, 2017, a comprehensi...

Geodetic very long baseline interferometry observations of radio telescopes, which are located in an immediate neighborhood, provide an optimal experimental setup for investigations in atmospheric refraction and system stability issues. In this study, a series of dedicated VLBI sessions with very short baselines, referred to as WHISP (Wettzell HIgh...

ZUSAMMENFASSUNG: Die geodätischen Raumverfahren VLBI, SLR, GNSS und DORIS bilden die Grundlage für die Realisierung globaler Referenzrahmen. Die Langzeitstabilität ihrer Referenzpunkte ist äußerst wichtig, da jede zeitliche Variation sich direkt auf den Referenzrahmen auswirkt. Während die Vermessung unbeweglicher Punkte wie GNSS- und DORIS-Antenne...

The quality of the links between the different space geodetic techniques (VLBI, SLR, GNSS and DORIS) is still one of the major limiting factors for the realization of a unique global terrestrial reference frame that is accurate enough to allow the monitoring of the Earth system, i.e., of processes like sea level change, postglacial rebound and sile...

The geodetic space techniques VLBI, SLR, GNSS and DORIS are the basis for the realisation of global reference frames. The long-term stability of their reference points is crucial since any temporal variation has a direct impact on the reference frame itself. While the terrestrial survey of non-moving reference points like GNSS- and DORIS antennas o...

High repetition SLR systems are very suitable for autonomous operation, because they provide sufficient feedback loop gain for the telescope servo operations. Once the SOS-W telescope became operational and started to contribute to the ILRS operations, we have started to implement autonomous tracking functions in order to support the simultaneous o...

The Geodetic Observatory Wettzell features three radiotelescopes. Local ties between the reference points are available from terrestrial precision surveying with an expected accuracy below 0.7 mm. In addition, local VLBI data analysis is currently investigated to provide independent vectors, and to provide quality feedback to the engineers. The pre...

Geodetic Very Long Baseline Interferometry (VLBI) uses radio telescopes as sensor networks to determine Earth orientation parameters and baseline vectors between the telescopes. The TWIN Telescope Wettzell 1 (TTW1), the first of the new 13.2 m diameter telescope pair at the Geodetic Observatory Wettzell, Germany, is currently in its commissioning p...

The integration of the new receiver frontend and the data acquisition backend was done during the VLBI campaign from January to February 2015. The new VLBI receiver was successfully installed into the antennas elevation cabin. The VLBI sampler ADS3000+ and the Mark5B+ were mounted into an existing and available rack in the DLR control room in paral...

Precise positioning applications using GNSS require corrections for the delay in the received satellite signal due to the atmosphere through which the signal travels. Many of these applications use the Zenith Total Delay (ZTD) estimated from climatology. The use of numerical weather prediction (NWP) models to provide estimates of ZTD for positionin...

GAULEO is Europe's future Global Navigation Satellite System (GNSS). The current state of development as well as its poten-tial performance is portrayed in this article. This comprises a brief description of the GALILEO system architecture (space, ground and user segments) including the final structure of the signal-in-space (SIS). Furthermore, sel...

The environmental satellite ENVISAT was successfully launched by the European Space Agency ESA in March 2002 and carries - among other sensors - a radar altimeter which is capable of measuring the height between sea surface and satellite with a precision of a few centimetres. Unfortunately, radar altimeters of this kind exhibit a bias which cannot...

Precise GPS positioning in kinematic mode over baselines as long as about 500 kilometers is exercised and discussed in this paper. No use of active networks -which supply correction parameters to efficiently mitigate atmospheric errors -is made. Instead, the necessary error terms like tropospheric and ionospheric delays are precisely modeled in the...