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The Joint Research Project SIMULTAN WP3.1: GNSS Campaigns and Research Tobias Kersten and Steffen Schön Institut für Erdmessung | Leibniz Universität Hannover | {kersten, schoen}@ife.uni-hannover.de Urban GNSS Sites and Campaign Design (a) SL03 (b) GRAV12 (c) GGP1 (d) HHDE (e) HH01 (f) HH09 Figure 1: Co-located urban GNSS sites as part of geo- monitoring networks to control and observe subsidence pro- cesses, (a-c) Bad Frankenhausen (Thuringia), (d-f) Hamburg Groß-Flottbek. SIMULTAN-Project I Sinkhole Instability, MULTiscale monitoring and ANalysis: gain a deeper understanding of the complex processes, interactions and characteristics of the underground and the surface interaction in urban environments, [Kersten et al., 2017a]. GNSS-Campaign Design in SIMULTAN I Multi-GNSS equipment (Leica GRX1200+GNSS, Novatel 703GGG, Leica AR25.R3) with height adaptor FG ANA 100B for precise height determination. I Four hour sessions, at least 3 independent repetitions per site. I Data recording (1 Hz) at co-located sites (GNSS, levelling, gravimetry). I Star-like GNSS monitoring network, fixed in local reference stations. Urban GNSS Sites I Urban infrastructure yields to variable and high multipath as well as challenging satellite geometry at each co-located site. I Short baselines of approx. 700-1800 m. Bad Frankenhausen - Network GRAV01 GRAV02 GRAV06 GRAV10 GRAV11 GRAV12 GRAV3 GRAV4 GRAV5 GRAV7 GRAV8 GRAV9 SL03 0 km 0.1 km 0.2 km map scale © GeoBasis-DE / BKG (2016) S o u t h E a s t K y f f h ä u s e r GRAV02 SL03 GGP1 ’Rathaus’ AP2 AP4 100 200 300 400 Altitude (m) 11°04' 11°06' 11°08' 51°20' 51°22' 51°24' Bad Frankenhausen (Thuringia, Germany) Legend GNSS / Levelling / Gravimetry Levelling / Gravimetry GNSS only GNSS baselines Levelling only (between AP2 and AP4) 0 1 2 km S E N W (a) GNSS network Bad Frankenhausen 15 15.5 16 GPS Time [h] -0.050 -0.025 0.000 0.025 0.050 DD [m] 0 15 30 45 60 75 90 Elevation [°] SNV 19 reference SVN 12 EL1C: 1,2cm EL5Q: 2,3cm EL7Q: 2,2cm EL8Q: 2,1cm (b) SL-12: DD and elevation versus GPS Time Figure 2: Analysis of Galileo GNSS sites, (a) network with indicated baseline, (b) double difference residuals for four hour session captured at GRAV12 (cf. Fig. 1b). I SL03: Local reference station (stability check by SAPOS R stations Erfurt (0209), Buttstädt (0221), Sondershausen (0200), Mühlhausen (0214)). I GRAV12: Co-located point in close vicinity to a concrete wall (located in the north of the GNSS site), challenging obstruction geometry present. I Baseline SL03-GRAV12 (SL-12): 190 m, significant impact of multipath detectable. I Multipath signatures detectable (sinusoidal) with frequencies of ≈20 minutes that lead to amplitudes in Galileo DDs (E5a, E5b and AltBOC E5a+b) although low noise is present. Highest noise on Galileo E1 signal detected, [Ruwisch et al., 2016]. Hamburg - Network I HHDE: Local reference station at DESY (Deutsches Elektronen-Synchrotron), stability check by SAPOS R stations (Lower Saxony) Buchholz (0680), Stade2 (1662), Lüneburg (0660). I HH01: Co-located site in a park with several trees which reduces satellite visibility at low elevations. I HH08: Site with close vicinity of a concrete wall, signals distorted by discounter market in north/east and several high trees in the south. Additionally, frequent traffic of trucks leads to signal interruptions. I Challenging satellite visibility at several GNSS stations. Figure 3: Combined geophysical network in Hamburg, Groß- Flottbek. 13 14 15 16 GPS Time [h] -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 DD [m] 0 15 30 45 60 75 90 Elevation [°] SVN 19 reference SVN 12 EL1C: 4,7 mm EL5Q: 4,5 mm EL7Q: 4,3 mm EL8Q: 4,3 mm (a) 13 14 15 16 GPS Time [h] -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 DD [m] 35 40 45 50 55 CN0 (EL1C) [dBHz] SVN 19 reference SVN 12 EL1C: 6,1mm EL5Q: 8,1mm EL7Q: 7,6mm EL8Q: 8,2mm (b) Figure 4: Galileo DD with individual standard deviation, shown here for selected baselines, (a) DE-01: DD and elevation versus GPS Time, (b) DE-08: DD and C/N 0 values versus GPS Time. Details Hamburg Studies of urban GNSS double differences show (cf. Fig. 3): I Baseline HHDE-HH01 (DE-01): 1.050 m, optimal results obtainable due to moderate obstructions. I Baseline HHDE-HH08 (DE-08): 830 m, frequently changing site geometry and challenging obstruction situation lead to significant noise in studied Galileo DD. HH01 - Residuals of DD individual signals close similar to each other. I Challenging geometry for optimal GNSS satellite tracking at urban GNSS sites. HH08 - Residuals of DD show higher magnitudes. I E1 indicates higher noise than other Galileo signals (ca. 80% below 2 mm), [Kersten und Schön, 2017]. I Modified Allan standard deviation results to averaging time of 20 sec (linear). I Signal of E1 (EL1C) corresponds to gradient of -1 (Flicker Phase Modulation (FPM)): DD superimposed by atmospheric delays as well as site specific multipath geometry (static and dynamic). Stability of Local Reference Stations April 2016 October 2016 01.12.2016 March 2017 -5.0 -2.5 0.0 2.5 5.0 [mm] " North " East " Up new SAPOS date (a) HHDE (out of Stade) April 2016 July 2016 October 2016 01.12.2016 April 2017 July 2017 -5.0 -2.5 0.0 2.5 5.0 [mm] " North " East " Up new SAPOS date (b) SL03 (out of Buttstädt) Figure 5: Comparisons of Epochs to test the stability of local reference stations, (a) local station HHDE in Hamburg (project HHX), (b) local station SL03 in Bad Frankenhausen (project BFH). Evaluation and Findings I L3 (ionosphere free) linear combination with noise of 6 mm used for fixing HHDE and SL03 via SAPOS R I Local references are stable; during campaigns no displacements are detected. I Longer time series importent to separate observations from superimposed noise (semi-annual signals, hydrology, etc.). I Common Geodetic Datum by SAPOS R (ETRS89) and new Datum provides improved consistency between physical (DHHN2016) and mathematical (ellipsoidal) heights; important for integration. I New SAPOS R Datum introduces heights differences of up to 20 mm in coordinates but improved consistency of GNSS ellipsoidal and physical DHHN2016-heights (gravity field, geoid). Conclusions and Further Steps I Study of Galileo observations in challenging, urban environments by [Ruwisch et al., 2016]. I Challenging satellite geometry improved by applying adaptive dynamic elevation masks (dynMsk) studied by [Icking et al., 2016]. I Campaigns finished and processing of epoch comparisons ongoing; solutions published frequently, [Kersten und Schön, 2017, Kersten et al., 2017b]. I Data provided through WebDAV server for both projects (HHX and BFH) for dedicated WP partners. Further steps I Development and evaluation of integrated model for levelling and gravimetric data sets, [Kersten et al., 2017a, Weise et al., 2017]. I Quantification and separation of superimposed signals as e.g. hydrological, atmospheric, seasonal variations and tidal effects. I Studies and application of GNSS low-cost reference stations in combination with urban infrastructure as street furniture like, e.g. streetlamps etc., [Kröger et al., 2017]. Acknowledgement & Funding Acknowledgement The authors thank the TLVerm Thuringia, the Glückauf Vermessung GmbH Sondershausen, the MEA2 Group of the German Electron Synchrotron (DESY) and the city of Bad Frankenhausen for their kind and friendly cooperation. Additional FG ANA 100B GNSS height adaptors and corresponding accessories were provided by the LGLN (Lower Saxony). The Center of Orbit Determination in Europe (CODE) is grateful acknowledged for providing freely high precise orbits and corresponding products. Funding The work in the project of SIMULTAN is funded under the grant 03G0843D by the Federal Ministry of Education and Research, based on a resolution by the German Bundestag. References Icking, L., Kersten, T., und Schön, S. (2016). Dynamische und adaptive Elevationsmasken zur Optimierung von GNSS-Netzen. In Geodätische Woche 2016, 11.-13. Oktober, Hamburg. Kersten, T., Kobe, M., Timmen, L., Schön, S., und Vogel, D. (2017a). Geodetic Monitoring of Subrosion-Induced Subsidence Processes in Urban Areas - Concept and Status Report. Journal of Applied Geodesy, 11(1):21–30. DOI: 10.1515/jag-2016-0029. Kersten, T. und Schön, S. (2017). Galileo for GNSS-Monitoring Networks in Urban Environments. In Proceedings of Ingenieurgeodäsie 17 - 18 Internationaler Ingenieurvermessungskurs, April 25.-29., Graz, Austria. DOI: 10.13140/RG.2.2.23052.10887. Kersten, T., Timmen, L., Schön, S., Weise, A., Kobe, M., und Gabriel, G. (2017b). Geodätisch-geophysikalisches Monitoring von Erdfallinstabilitäten - Ergebnisse der SIMULTAN-Kampagnen 2015-2017. In Geodätische Woche 2016, 26.-28. September, Berlin. Kröger, J., Kersten, T., und Schön, S. (2017). GPS/GNSS Low Cost Permanent-Stationen für urbane Monitoringnetze. In Geodätische Woche 2016, 26.-28. September, Berlin. Ruwisch, F., Kersten, T., und Schön, S. (2016). GNSS-Doppeldifferenzanalyse für urbane Monitoring-Ansätze. In Geodätische Woche 2016, 11.-13. Oktober, Hamburg. Weise, A., Kersten, T., Schön, S., Timmen, L., und Vogel, D. (2017). Deformationsüberwachung mit Gravimetrie? Ein Experiment im Erdfallgebiet in Hamburg-Flottbek. In Proceedings of 77. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, March 27.-30., Potsdam, Germany. (Projekträger Jülich :: Status-Seminar Dresden, Grant-ID: 03G0843D) Created with L A T E X
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