The Joint Research Project SIMULTANWP3.1: GNSS Campaigns and ResearchTobias 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-ProjectI Sinkhole Instability, MULTiscale monitoring and

ANalysis: gain a deeper understanding of thecomplex processes, interactions andcharacteristics of the underground and thesurface interaction in urban environments,[Kersten et al., 2017a].

GNSS-Campaign Design in SIMULTANI Multi-GNSS equipment (Leica

GRX1200+GNSS, Novatel 703GGG, LeicaAR25.R3) with height adaptor FG ANA 100B forprecise height determination.

I Four hour sessions, at least 3 independentrepetitions per site.

I Data recording (1 Hz) at co-located sites(GNSS, levelling, gravimetry).

I Star-like GNSS monitoring network, fixed inlocal reference stations.

Urban GNSS SitesI Urban infrastructure yields to variable and high

multipath as well as challenging satellitegeometry 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

GRAV02SL03GGP1

’Rathaus’

AP2

AP4

100

200

300

400Altitude (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)

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km

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(a) GNSS network Bad Frankenhausen

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SNV 19reference SVN 12EL1C: 1,2cmEL5Q: 2,3cmEL7Q: 2,2cmEL8Q: 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 sessioncaptured 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 inGalileo DDs (E5a, E5b and AltBOC E5a+b) although low noise is present. Highest noise on Galileo E1signal detected, [Ruwisch et al., 2016].

Hamburg - Network

I HHDE: Local reference station at DESY(Deutsches Elektronen-Synchrotron), stabilitycheck by SAPOS R© stations (Lower Saxony)Buchholz (0680), Stade2 (1662), Lüneburg(0660).

I HH01: Co-located site in a park with severaltrees which reduces satellite visibility at lowelevations.

I HH08: Site with close vicinity of a concrete wall,signals distorted by discounter market innorth/east and several high trees in the south.Additionally, frequent traffic of trucks leads tosignal interruptions.

I Challenging satellite visibility at several GNSSstations.

Figure 3: Combined geophysical network in Hamburg, Groß-Flottbek.

13 14 15 16GPS Time [h]

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SVN 19reference SVN 12EL1C: 4,7 mmEL5Q: 4,5 mmEL7Q: 4,3 mmEL8Q: 4,3 mm

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SVN 19reference SVN 12EL1C: 6,1mmEL5Q: 8,1mmEL7Q: 7,6mmEL8Q: 8,2mm

(b)

Figure 4: Galileo DD with individual standard deviation, shown here for selected baselines, (a) DE-01: DD and elevation versus GPSTime, (b) DE-08: DD and C/N0 values versus GPS Time.

Details HamburgStudies 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 obstructionsituation 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 superimposedby 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

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" North" East" Up

new SAPOS date

(a) HHDE (out of Stade)

April 2016

July 2016

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July 2017-5.0

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" North" East" Up

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(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 FindingsI 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 consistencybetween 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 improvedconsistency 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 stepsI 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, seasonalvariations and tidal effects.

I Studies and application of GNSS low-cost reference stations in combination with urban infrastructure asstreet 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 Groupof 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 (LowerSaxony). The Center of Orbit Determination in Europe (CODE) is grateful acknowledged for providing freely high preciseorbits and corresponding products.

Funding The work in the project of SIMULTAN is funded under the grant 03G0843D by the Federal Ministry of Education andResearch, 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. InGeodätische Woche 2016, 11.-13. Oktober, Hamburg.

Kersten, T., Kobe, M., Timmen, L., Schön, S., und Vogel, D. (2017a). Geodetic Monitoring of Subrosion-Induced SubsidenceProcesses 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 ofIngenieurgeodäsie 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 vonErdfallinstabilitäten - 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. InGeodätische Woche 2016, 26.-28. September, Berlin.

Ruwisch, F., Kersten, T., und Schön, S. (2016). GNSS-Doppeldifferenzanalyse für urbane Monitoring-Ansätze. In GeodätischeWoche 2016, 11.-13. Oktober, Hamburg.

Weise, A., Kersten, T., Schön, S., Timmen, L., und Vogel, D. (2017). Deformationsüberwachung mit Gravimetrie? Ein Experimentim Erdfallgebiet in Hamburg-Flottbek. In Proceedings of 77. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, March27.-30., Potsdam, Germany.

(Projekträger Jülich :: Status-Seminar Dresden, Grant-ID: 03G0843D) Created with LATEX