References of "Warnant, René"
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See detailTotal Electron Content monitoring using triple frequency GNSS data: a three-step approach
Spits, Justine; Warnant, René ULg

Conference (2008)

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See detailDetection of small-scale structures in the neutral atmosphere using double differences of GNSS measurements
Brenot, Hugues; Lejeune, Sandrine; Warnant, René ULg

Conference (2008)

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See detailIonosphere Modelling for GALILEO Single Frequency Users
Bidaine, Benoît ULg; Warnant, René ULg

Poster (2007, October 17)

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See detailReal time TEC monitoring using triple frequency GNSS data : a three step approach
Spits, Justine; Warnant, René ULg

in Proceedings of the First International Colloquium - Scientific and Fundamental Aspects of the Galileo Programme (2007, October)

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See detailAssessment of the NeQuick Model at Mid-latitudes using GPS TEC and Ionosonde Data
Bidaine, Benoît ULg; Warnant, René ULg

in First Colloquium Scientific and Fundamental Aspects of the Galileo Programme (2007, October)

The ionosphere plays a crucial role in Global Navigation Satellite Systems (GNSS) accuracy. In extreme cases, this electrically charged part of the atmosphere can lead to errors in positioning exceeding ... [more ▼]

The ionosphere plays a crucial role in Global Navigation Satellite Systems (GNSS) accuracy. In extreme cases, this electrically charged part of the atmosphere can lead to errors in positioning exceeding 100 $m$. At first approximation, ionospheric effects depend mainly on the total content in free electrons of the ionosphere ("total electron content", TEC). The modelling of the latter parameter reveals thus itself critical in particular for single frequency receivers, the most common ones constituting the mass market. In the framework of GALILEO, the NeQuick model has been chosen to this extent and will be integrated into a global algorithm providing the users with daily updated information. In order to reach the specified correction level, the model itself and its latest evolutions as well as its use for GALILEO are investigated. As a first step in a thorough analysis, we take benefit of ionosonde and GPS TEC data from the Dourbes Geophysical Observatory (Belgium) to study the mid-latitudes. Constraining the model with ionosonde measurements, we first investigate the difference between GPS-derived vertical TEC (vTEC) for Dourbes station and corresponding values from NeQuick for the latest years for solar maximum in 2002 and minimum in 2006. With this approach, we reach residual errors of about 20% RMS for 2002 and 30% for 2006. Through a focusing process, we identify then gradually best and worst months and days for which we observe the evolution between two versions of NeQuick. We highlight among others improvements from the latest modification in the topside formulation which appears clearly in the electron density profiles examined at the end of the assessment. [less ▲]

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See detailAssessment of the NeQuick Model at Mid-latitudes using GPS TEC and Ionosonde Data
Bidaine, Benoît ULg; Warnant, René ULg

Conference (2007, July 11)

The ionosphere plays a crucial role in GNSS accuracy. In extreme cases, this electrically charged part of the atmosphere can lead to errors in positioning exceeding 100m. At first approximation, the ... [more ▼]

The ionosphere plays a crucial role in GNSS accuracy. In extreme cases, this electrically charged part of the atmosphere can lead to errors in positioning exceeding 100m. At first approximation, the ionospheric effect depends on the frequency of the incident signal and on the total content in free electrons of the ionosphere (“total electron content”, TEC) which is the integral of the electron density on the path between the satellite and the receiver. The modelling of this parameter reveals then itself to be critical in particular for single-frequency receivers, the most common ones constituting the mass market, but also for multiple-frequency devices which will comprise a fallback mode in single frequency within the framework of critical applications such as civil aviation where the level of precision must be guaranteed in all circumstances. The NeQuick model, which has been chosen for correcting the ionospheric error contribution in GALILEO single frequency users, calculates the electron density at a given point of the ionosphere according to the time conditions and the solar activity. This electron density can be integrated along the path from the receiver to the considered satellite to provide the TEC. The NeQuick model depends on a parameter Az (“effective ionization level”) which will be daily updated by the GALILEO ground stations to give the solar activity information to the model. In order to reach the ionosphere error correction level objective (70% or 20 TECu whichever is larger), the model itself as well as its use for GALILEO are investigated. Different situations have to be considered: different latitude regions (space conditions), different hours, seasons and years (time conditions) and specific phenomena appearance (magnetic storms, Travelling Ionospheric Disturbances – TIDs). In addition the results can be compared to different data sets among which GPS slant or vertical TEC measurements, Global Ionospheric Maps, ionosonde profiles, topside soundings but also other ionosphere models results such as IRI. As a first step in a thorough comparison process, we take benefit of various ionosphere data from the Dourbes Observatory (Belgium) where ionosonde and GPS TEC data are available on a period of more than one solar cycle, to study the mid-latitudes. We first investigate the difference between GPS-derived vTEC for Dourbes station and vTEC values from NeQuick for the latest years (between solar maximum in 2000 and minimum in 2006) in order to observe the temporal dependencies towards Universal Time, season and solar activity. The paper analyses the different situations when NeQuick fails to represent TEC in an adequate way to provide an efficient correction for navigation. Ionosonde measurements will help in the interpretation of these situations. [less ▲]

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See detailStatistical study of ionospheric small-scale irregularities at mid-latitudes using GPS measurements
Wautelet, Gilles ULg; Warnant, René ULg

Conference (2007, July 11)

At the present time, Global Navigation Satellite Systems (GNSS) allow to obtain a precision of a few centimeters in real time using positioning techniques like the so-called Real Time Kinematics (RTK ... [more ▼]

At the present time, Global Navigation Satellite Systems (GNSS) allow to obtain a precision of a few centimeters in real time using positioning techniques like the so-called Real Time Kinematics (RTK). Nowadays, the ionosphere remains the most important error source affecting such GNSS applications. Indeed, the presence of small-scale irregular structures in the Total Electron Content (TEC) can strongly affect the reliability and the precision of high precision real time positioning applications. Those small-scale structures can have several origins: Traveling Ionospheric Disturbances, "noise-like" variability in TEC, scintillations. The Royal Meteorological Institute of Belgium (RMI) has developed a software which allows to monitor the TEC using GPS measurements (at one station). The software can also be used to detect small-scale irregularities in TEC by monitoring TEC temporal gradients (i.e. rate of change). The RMI has applied this software to the GPS data collected at Brussels from April 1993 up to now what represents a period of more than a Solar Cycle. The results obtained from this GPS-TEC software will be presented. First, the paper analyzes the different types of small-scale structures which have been observed in TEC. Then, a statistical study of those ionospheric irregularities is presented; we shall analyze their probability of occurrence and their amplitude (in TECU/min) depending on daytime, season, solar activity, geomagnetic activity... The results of our study which is financed by the GNSS Supervising Authority will allow to have a better understanding of the usual case/worst case conditions encountered in high precision positioning applications based on GNSS. [less ▲]

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See detailCOST 296 Working Group 3 “Space-based systems” activities and results
Warnant, René ULg

Conference (2007, July)

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See detailQuantification of Tropospheric Activity according to Double Differences Analysis of GNSS Phases Records.
Brenot, Hugues; Lejeune, Sandrine; Wautelet, Gilles ULg et al

Conference (2007)

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See detailSpace Weather influence on satellite based navigation and precise positioning
Warnant, René ULg; Lejeune, Sandrine; Bavier, Michaël

in Lilensten, Jean (Ed.) Space Weather - Research towards Applications in Europe (2007)

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See detailRelevance of active faulting and seismicity studies to assessments of long-term earthquake activity and maximum magnitude in intraplate northwest Europe, between the Lower Rhine Embayment and the North Sea
Camelbeeck, Thierry; Vanneste, Kris; Alexandre, Pierre ULg et al

in Stein, S.; Mazzotti, S. (Eds.) Continental Intraplate Earthquakes: Science, Hazard and Policy Issues (2007)

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Peer Reviewed
See detailIonospheric and geomagnetic conditions during periods of degraded GPS position accuracy : 2. RTK events during disturbed and quiet geomagnetic conditions
Warnant, René ULg; Kutiev, Ivan; Marinov, Pencho et al

in Advances in Space Research (2007), 39(5), 881-888

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See detailProject Office – Mid-term progress report
Warnant, René ULg

Report (2007)

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See detailProject Office - First synthetic report
Warnant, René ULg

Report (2007)

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See detailHybrid Model for Kp prediction, combining solar wind and magnetometer data
Kutiev, Ivan; Andonov, B.; Muhtarov, P. et al

Conference (2007)

Detailed reference viewed: 18 (0 ULg)
See detailReal time TEC monitoring using triple frequency GNSS data : a three step approach
Spits, Justine; Warnant, René ULg

Conference (2007)

Detailed reference viewed: 11 (1 ULg)
See detailModelling the medium-scale TEC structures, observed by Belgian GPS receiver network
Kutiev, Ivan; Marinov, P.; Fidanova, S. et al

Conference (2007)

Detailed reference viewed: 8 (0 ULg)
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See detailNear real time assessment of the ionosphere effect on high accuracy GNSS applications which require ambiguity resolution
Lejeune, Sandrine; Warnant, René ULg

in Proceedings of the 2nd COST296 Workshop (2006, October)

Detailed reference viewed: 15 (2 ULg)