The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy

Pollinger, Florian; Baselga, Sergio; Courde, Clément; Eschelbach, Cornelia; García-Asenjo, Luis; Garrigues, Pascual; Guillory, Joffray; Hedekvist, Per Olof; Helojärvi, Tuomas; Jokela, Jorma; Kallio, Ulla; Klügel, Thomas; Köchert, Paul; Lösler, Michael; Luján, Raquel; Meyer, Tobias; Neyezhmakov, Pavel; Pesce, Damien; Pisani, Marco; Poutanen, Markku; Prellinger, Günther; Sauthoff, Anni; Seppä, Jeremias; Truong, Daniel; Underwood, Robin; Wezka, Kinga; Wallerand, Jean‐Pierre; Wiśniewski, Mariusz

doi:10.1007/s12518-022-00487-3

Cited by 6 publications

(6 citation statements)

References 43 publications

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“…• solving the system of equations to obtain floating ambiguities and then rounding them to their nearest integer. • setting to zero the coordinate corrections dX j = 0, dY j = 0, and dZ j = 0 in equation (10), which makes sense due to the accurate initial PPP processing, and obtaining ambiguities by solving the simplified system of equations: first as floating ambiguities and then rounded to their nearest integer.…”

Section: Additional Remarksmentioning

confidence: 99%

“…The JRP SIB60 Metrology for long distance surveying project was concerned with lengths up to 1 km. Recently, this consortium renewed and united in a new research project, GeoMetre [6,10], that is aimed at improving the traceability of geodetic references to the SI meter definition with the focus extended to lengths up to 5 km, including the development of novel distance meters and a novel strategy for GNSSbased distance determination for this range. The presentation of this strategy is the objective of the current paper, a strategy which provides the user with the detailed analysis of the uncertainty in the different error sources and its propagation through the particular double-differenced equations up to the determination of the baseline distance, whose final value can be now accompanied with the corresponding uncertainty budget, something which is not possible to be carried out by the existing software packages and has prevented so far the use of GNSS techniques for metrological purposes.…”

Section: Introductionmentioning

confidence: 99%

“…In accordance with the objectives of the Geometre project, we want to improve the method now so that its application range can be extended to baselines of up to 5 km with significant (or not) height difference. The improved methodology for this GBDM will be referred to as GBDM+ two observation campaigs are planned during 2022 where the GBDM+ methodology will be contrasted with refractivity compensated two-color EDM prototypes in two singular sites: the CERN geodetic network and the European primary reference baseline EURO5000 [10].…”

Section: Introductionmentioning

confidence: 99%

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GBDM+: an improved methodology for a GNSS-based distance meter

Baselga

García-Asenjo

Garrigues

et al. 2022

Meas. Sci. Technol.

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The determination of distances consistent with the definition of the base unit of length in the International System of Units (SI), the SI meter, with uncertainties of less than 1 ppm up to 5 km in the open air is a current challenge that is being increasingly required for different applications, including the determination of local ties, calibration baselines, and high precision geodetic metrology in singular scientific and engineering projects. The required knowledge of the index of refraction of the propagating medium at the same level of 1 ppm is a hard limit to the use of precise electronic distance meters, which has motivated the recent development of new two-color, refractivity compensated, electronic distance meter prototypes. As an alternative, the use of Global Navigation Satellite Systems (GNSS) could benefit from their high scale stability although the lack of appropriate estimation of the uncertainties in their sources of error and their unknown propagation into the final result during the data processing has prevented a rigorous uncertainty analysis and, therefore, the use of GNSS for absolute distance determination. Stemming from our initial methodology for a GNSS-Based Distance Meter (GBDM) that was restricted to relatively horizontal baselines and distances up to 1 km only, we have improved the method so that its application range is extended to baselines of up to 5 km with a possibly significant height difference so that it provides the final baseline distance with the corresponding uncertainty derived from the uncertainties in the different error sources rigorously propagated through the equations by which the distance is finally determined. This improved methodology, named as GBDM+, constitutes a significant step forward in the application of GNSS to open air length metrology.

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Section: Additional Remarksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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GBDM+: an improved methodology for a GNSS-based distance meter

Baselga

García-Asenjo

Garrigues

et al. 2022

Meas. Sci. Technol.

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“…only a few micrometres. The distributions of the optical path lengths at 780 nm and 1560 nm corresponding to this experiment, of standard deviations around 5 µm over 1 min despite atmospheric turbulences, were presented as preliminary results in [38].…”

Section: Displacement Measurementsmentioning

confidence: 95%

A sub-millimetre two-wavelength EDM that compensates the air refractive index: uncertainty and measurements up to 5 km

Guillory,

Truong,

Wallerand

et al. 2023

Meas. Sci. Technol.

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Distance measurements over several kilometres with a sub-millimetre uncertainty are required for deformation monitoring in fields such as geodesy or civil engineering where well-controlled scale is critical. This paper presents a two-wavelength electro-optical distance meter (EDM) capable of such measurements and traceable to the SI (Système International d’unités). It is based on simultaneous measurements of optical path lengths, at two wavelengths, one at 780 nm and the other at 1560 nm, the dispersion between the two wavelengths allowing real-time compensation of the air refractive index along the optical paths. The uncertainty budget of this EDM has been established, taking into account both the telemetric and the mechanical contributions. One of the main sources of errors is crosstalk, which originates mainly from the optical splitters acting as circulators and becomes more pronounced for lower received powers over longer distances. For signal-to-crosstalk ratios (SCRs) higher than 60 dB, the instrumental uncertainty in the air-index compensated distance was assessed to be 320 µm (k = 1). In the field, two distance measurements, one over 2.6 km, the other over 5.4 km, were carried out over a period of up to 6 days, and for a temperature and pressure varying by as much as 10 °C and 17 hPa. For each distance, the standard deviation of the Gaussian fit of the experimental points was less than 250 µm. This level of refractivity compensation demonstrates that the developed instrument works properly. In addition, standard deviations lower than 140 µm were achieved for displacement measurements at distances around 2.6 km and 5.4 km. All these results were obtained for SCRs higher than 60 dB. Finally, solutions are proposed for mitigating the effect of high crosstalk values on instrumental uncertainty.

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“…The EURAMET project GeoMetre (2020) takes up the topic of improving the quality and reliability of global reference frames by, for instance, traceably transforming local ties to the global reference frame (Pollinger et al, 2022). Also part of this research project is the further development of measurement and analysis strategies for the determination of the reference points of telescope-based space geodetic techniques.…”

Section: Introductionmentioning

confidence: 99%

A feasibility study for accelerated reference point determination using close range photogrammetry

Eschelbach

Lösler

2022

Proceedings of the 5th Joint International Symposium on Deformation Monitoring - JISDM 2022

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The Global Geodetic Observing System (GGOS) aims for an accuracy of 1 mm in position concerning a global geodetic reference frame such as the International Terrestrial Reference Frame (ITRF). To derive a global frame, several space geodetic techniques are combined. The combination procedure requires the geometric relations between the invariant reference points of these techniques, the so-called local tie vectors. Each space geodetic technique defines its reference point individually, so the determination of the position of the reference point varies significantly between techniques. Within the international GeoMetre project, measurement systems and analysis strategies are developed to improve the quality of local tie vectors and, thus, the quality of the resulting global frame. The use of close range photogrammetry to determine the reference point of a telescope used for Satellite Laser Ranging (SLR) at the GGOS core station Wettzell in September 2020 is considered as a milestone in this project. This contribution deals with a novel approach for an accelerated reference point determination using close range photogrammetry. In comparison to the conventional photogrammetric approach, published so far, this new approach leads to a significant reduction in recording time. However, in case of inappropriate measurement configuration the approach also bears the risk of biased results. Most importantly, the new approach has the potential to be automated, which is one of the primary calls of GGOS for reference point determinations.

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The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy

Cited by 6 publications

References 43 publications

GBDM+: an improved methodology for a GNSS-based distance meter

GBDM+: an improved methodology for a GNSS-based distance meter

A sub-millimetre two-wavelength EDM that compensates the air refractive index: uncertainty and measurements up to 5 km

A feasibility study for accelerated reference point determination using close range photogrammetry

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