scholarly journals Hybrid Data Fusion and Tracking for Positioning with GNSS and 3GPP-LTE

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Christian Mensing ◽  
Stephan Sand ◽  
Armin Dammann
Keyword(s):  
Data Fusion ◽  
Global Navigation Satellite Systems ◽  
Optimum Conditions ◽  
Satellite Systems ◽  
3Gpp Lte ◽  
User Simulation ◽  
Multipath Effects ◽  
Hybrid Data ◽  
Global Navigation Satellite ◽  
Communications System

Global navigation satellite systems (GNSSs) can provide reliable positioning information under optimum conditions, where at least four satellites can be accessed with sufficient quality. In critical situations, for example, urban canyons or indoor, due to blocking of satellites by buildings and severe multipath effects, the GNSS performance can be decreased substantially. To overcome this limitation, we propose to exploit additionally information from communications systems for positioning purposes, for example, by using time difference of arrival (TDOA) information. To optimize the performance, hybrid data fusion and tracking algorithms can combine both types of sources and further exploit the mobility of the user. Simulation results for different filter types show the ability of this approach to compensate the lack of satellites by additional TDOA measurements from a future 3GPP-LTE communications system. This paper analyzes the performance in a fairly realistic manner by taking into account ray-tracing simulations to generate a coherent environment for GNSS and 3GPP-LTE.

scholarly journals Investigating GNSS multipath effects induced by co-located Radar Corner Reflectors

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Thomas Fuhrmann ◽  
Matthew C. Garthwaite ◽  
Simon McClusky
Keyword(s):  
Land Surface ◽  
Reference Frames ◽  
Surface Deformation ◽  
Signal To Noise Ratio ◽  
Ground Plane ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Multipath Effects ◽  
Global Navigation Satellite ◽  
Relative Measurements

Abstract Radar Corner Reflectors (CR) are increasingly used as reference targets for land surface deformation measurements with the Interferometric Synthetic Aperture Radar (InSAR) technique. When co-located with ground-based Global Navigation Satellite Systems (GNSS) infrastructure, InSAR observations at CR can be used to integrate relative measurements of surface deformation into absolute reference frames defined by GNSS. However, CR are also a potential source of GNSS multipath effects and may therefore have a detrimental effect on the GNSS observations. In this study, we compare daily GNSS coordinate time series and 30-second signal-to-noise ratio (SNR) observations for periods before and after CR deployment at a GNSS site. We find that neither the site coordinates nor the SNR values are significantly affected by the CR deployment, with average changes being within 0.1 mm for site coordinates and within 1 % for SNR values. Furthermore, we generate empirical site models by spatially stacking GNSS observation residuals to visualise and compare the spatial pattern in the surroundings of GNSS sites. The resulting stacking maps indicate oscillating patterns at elevation angles above 60 degrees which can be attributed to the CR deployed at the analysed sites. The effect depends on the GNSS antenna used at a site with the magnitude of multipath patterns being around three times smaller for a high-quality choke ring antenna compared to a ground plane antenna without choke rings. In general, the CR-induced multipath is small compared to multipath effects at other GNSS sites located in a different environment (e. g. mounted on a building).

scholarly journals GPS Multipath Analysis Using Fresnel Zones

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 25 ◽  
Author(s):  
Florian Zimmermann ◽  
Berit Schmitz ◽  
Lasse Klingbeil ◽  
Heiner Kuhlmann
Keyword(s):  
Fresnel Zone ◽  
Position Estimation ◽  
Global Navigation Satellite Systems ◽  
Limiting Factors ◽  
Systematic Effect ◽  
Satellite Systems ◽  
Multipath Effects ◽  
The Individual ◽  
Global Navigation Satellite ◽  
Fresnel Zones

GNSS (Global Navigation Satellite Systems) multipath has been subject to scientific research for decades and although numerous methods and techniques have already been developed to mitigate this effect, it is still one of the accuracy-limiting factors in many GNSS applications. Since multipath is highly dependent on the individual antenna environment, there is still a need for new methods and further investigations to increase the understanding of this systematic effect. In this paper, the concept of Fresnel zones is applied to two different aspects of multipath. First, Fresnel zones are determined for the line-of-sight transmission between satellite and receiver. By comparing the boundary of the Fresnel zones to an obstruction adaptive elevation mask, potentially diffracted signals can be identified and excluded from the position estimation process. Both the percentage of epochs with fixed ambiguities and the positioning accuracy can be increased by the proposed method. Second, Fresnel zones are used to analyze the multipath induced by a horizontal and spatially-limited reflector. The comparison of simulated and real signal-to-noise (SNR) observations reveals a relationship between the percentage of the overlap of the Fresnel zone and reflector and the occurrence of multipath. It is found that an overlap of 50% is sufficient to induce multipath effects. This is of special interest, since this does not confirm theoretical assumptions of the multipath theory.

Hydrogeophysical Survey of Groundwater Development at Okada Community Ovia North – East L.G.A. Edo State

2018 ◽  
Vol 2 (1) ◽  
pp. 39-45
Author(s):  
M. O. Ehigiator
Keyword(s):  
Global Navigation Satellite Systems ◽  
Geophysical Investigation ◽  
Satellite Systems ◽  
North East ◽  
Long Time ◽  
Electrical Sounding ◽  
Edo State ◽  
Global Navigation Satellite ◽  
Water Problems ◽  
Aquifer Unit

Geophysical investigation was conducted at Okada community in ovia North Local Govertment area of Edo state to determine the prospect of aquifer zone. The Petrozenith PZ-02 Terrameter, one of the Electrical Resistivity Equipment was used to conduct a Vertical Electrical Sounding (VES) in the study area. The Garmin Etrex 10 Global Navigation satellite systems (GNSS) was used to acquire Geodetic coordinates of point where VES observations were made. This research was carried out as a pre-drilling Hydro-geophysical survey conducted for the purpose of surveying and studying the proposed water borehole site at Okada Community that has suffered acute water problems for a very long time. There have been series of boreholes drilled in the studied area but all are dry wells. This survey was conducted to investigate the subsurface complexity of the sites in respect of lithology and to recommend the total drill depth based on the prospective aquifer unit so identified. Result of interpretation suggests that the area is underlain with substantive aquiferous formation but at a depth not exceeding 121.60 m (398.95 ft), which is the lower aquifer unit. The value of elevation at point of observation referenced to mean sea level is 94 m.

scholarly journals Forty-three years of absolute gravity observations of the Fennoscandian postglacial rebound in Finland

2021 ◽  
Vol 95 (2) ◽  
Author(s):  
Mirjam Bilker-Koivula ◽  
Jaakko Mäkinen ◽  
Hannu Ruotsalainen ◽  
Jyri Näränen ◽  
Timo Saari
Keyword(s):  
Gravity Data ◽  
Gravity Change ◽  
Global Navigation Satellite Systems ◽  
Absolute Gravity ◽  
Data Sets ◽  
Postglacial Rebound ◽  
Land Uplift ◽  
Satellite Systems ◽  
Gravity Measurements ◽  
Global Navigation Satellite

AbstractPostglacial rebound in Fennoscandia causes striking trends in gravity measurements of the area. We present time series of absolute gravity data collected between 1976 and 2019 on 12 stations in Finland with different types of instruments. First, we determine the trends at each station and analyse the effect of the instrument types. We estimate, for example, an offset of 6.8 μgal for the JILAg-5 instrument with respect to the FG5-type instruments. Applying the offsets in the trend analysis strengthens the trends being in good agreement with the NKG2016LU_gdot model of gravity change. Trends of seven stations were found robust and were used to analyse the stabilization of the trends in time and to determine the relationship between gravity change rates and land uplift rates as measured with global navigation satellite systems (GNSS) as well as from the NKG2016LU_abs land uplift model. Trends calculated from combined and offset-corrected measurements of JILAg-5- and FG5-type instruments stabilized in 15 to 20 years and at some stations even faster. The trends of FG5-type instrument data alone stabilized generally within 10 years. The ratio between gravity change rates and vertical rates from different data sets yields values between − 0.206 ± 0.017 and − 0.227 ± 0.024 µGal/mm and axis intercept values between 0.248 ± 0.089 and 0.335 ± 0.136 µGal/yr. These values are larger than previous estimates for Fennoscandia.

scholarly journals Injury prevention in Super-G alpine ski racing through course design

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthias Gilgien ◽  
Philip Crivelli ◽  
Josef Kröll ◽  
Live S. Luteberget ◽  
Erich Müller ◽  
...  
Keyword(s):  
Ground Reaction Force ◽  
Course Design ◽  
Reaction Force ◽  
Global Navigation Satellite Systems ◽  
World Cup ◽  
Satellite Systems ◽  
Turn Radius ◽  
Energy Dissipated ◽  
Global Navigation Satellite ◽  
High Level

AbstractIn Super-G alpine ski racing mean speed is nearly as high as in Downhill. Hence, the energy dissipated in typical impact accidents is similar. However, unlike Downhill, on Super-G courses no training runs are performed. Accordingly, speed control through course design is a challenging but important task to ensure safety in Super-G. In four male World Cup alpine Super-G races, terrain shape, course setting and the mechanics of a high-level athlete skiing the course were measured with differential global navigation satellite systems (dGNSS). The effects of course setting on skier mechanics were analysed using a linear mixed effects model. To reduce speed by 0.5 m/s throughout a turn, the gate offset needs to be increased by + 51%. This change simultaneously leads to a decrease in minimal turn radius (− 19%), an increase in impulse (+ 27%) and an increase in maximal ground reaction force (+ 6%). In contrast, the same reduction in speed can also be achieved by a − 13% change in vertical gate distance, which also leads to a small reduction in minimal turn radius (− 4%) impulse (− 2%), and no change in maximal ground reaction force; i.e. fewer adverse side effects in terms of safety. It appears that shortening the vertical gate distance is a better and safer way to reduce speed in Super-G than increasing the gate offset.

scholarly journals Investigation of Ionospheric Response to June 2009 Sarychev Peak Volcano Eruption

2021 ◽  
Vol 13 (4) ◽  
pp. 638
Author(s):  
Nikolay Shestakov ◽  
Alexander Orlyakovskiy ◽  
Natalia Perevalova ◽  
Nikolay Titkov ◽  
Danila Chebrov ◽  
...  
Keyword(s):  
Acoustic Mode ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Field Zone ◽  
Ionospheric Response ◽  
Satellite Systems ◽  
Volcano Eruption ◽  
Close Proximity ◽  
Global Navigation Satellite ◽  
Sarychev Peak

Global Navigation Satellite Systems have been extensively used to investigate the ionosphere response to various natural and man-made phenomena for the last three decades. However, ionospheric reaction to volcano eruptions is still insufficiently studied and understood. In this work we analyzed the ionospheric response to the 11–16 June 2009 VEI class 4 Sarychev Peak volcano eruption by using surrounding Russian and Japanese GPS networks. Prominent covolcanictotal electron content (TEC)ionospheric disturbances (CVIDs) with amplitudes and periods ranged between 0.03–0.15 TECU and 2.5–4.5 min were discovered for the three eruptive events occurred at 18:51 UT, 14 June; at 01:15 and 09:18 UT, 15 June 2009. The estimates of apparent CVIDs velocities vary within 700–1000 m/s in the far-field zone (300–900 km to the southwest from the volcano) and 1300–1800 m/s in close proximity toSarychev Peak. The characteristics of the observed TEC variations allow us to attribute them to acoustic mode. The south-southwestward direction is preferred for CVIDs propagation. We concluded that the ionospheric response to a volcano eruption is mainly determined by a ratio between explosion strength and background ionization level. Some evidence of secondary (F2-layer) CVIDs’ source eccentric location were obtained.

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