Best performances for the SPP and PPP algorithms in terms of reliability are obtained by hybrid strategies targeting both the stochastic modelling and the integrity monitoring stages of the algorithms.Les systèmes globaux de positionnement et de navigation par satellites (Global Navigation Satellite Systems – GNSSs) occupent désormais une place prépondérante dans notre société moderne.
Then, this Ph D thesis focusses on the spatiotemporal characteristics of ionospheric scintillations by exploiting spatial analysis techniques applied to scintillation measurements collected through the experimental ISMR network located in Brazil.
Spatial analysis techniques consider densified ionospheric scintillation skyplots composed of Ionospheric Pierce Points (IPPs) as spatial samples whose geometric and attribute components evolve over time as satellites are orbiting the Earth and as ionospheric conditions change.
As the performances of the PPP algorithm rely on the precision of carrier phase measurements, the PPP algorithm is more sensitive to ionospheric scintillations than the SPP algorithm, which is based on code pseudorange measurements exclusively.
In case of active ionospheric scintillation conditions, the Root-Mean-Square Error (RMSE) of the tridimensional PPP solution can be as high as 6.73 m and its success rate as low as 50% by comparison to 0.18 m and about 100%, respectively, during quiescent conditions.
Finally, this Ph D thesis describes the design and benchmarks the performances of several categories of prototype mitigation strategies against ionospheric scintillations that target the stochastic modelling and the integrity monitoring stages of the SPP and PPP algorithms.
The design of the strategies is based on several types of ionospheric scintillation skymaps and the benchmark of their performances relies on the definition of several specific performance parameters.Tout d’abord, cette Thèse de Doctorat présente une analyse statistique basée sur des mesures effectuées par un réseau de récepteurs de type ISMR implanté à proximité de l’équateur magnétique, au Brésil.Les mesures ont été collectées durant l’année 2014, c’est-à-dire durant le (second) pic d’intensité du dernier maximum solaire (cycle solaire n°24).Globally, all the prototype mitigation strategies designed in the framework of this Ph D thesis contribute to increase the accuracy, continuity and reliability performances of the SPP and PPP algorithms during low-to-moderate ionospheric scintillations.Strategies associated with ionospheric scintillation skymaps based on local spatial autocorrelation statistics outperform strategies based on interpolated skymaps.Etant donné que les hautes performances de l’algorithme PPP dépendent de la précision de mesures de phase, l’algorithme PPP est davantage sensible aux scintillations ionosphériques que l’algorithme SPP, basé exclusivement sur des mesures de code.En cas de scintillations ionosphériques sévères, la racine carrée de l’erreur quadratique moyenne (Root-Mean-Square Error – RMSE) de la solution PPP peut atteindre la valeur extrême de 6.73 m et s’associer à un taux de succès aussi faible que 50%, par comparaison à une valeur de 0.18 m et de 100%, respectivement, pendant des conditions nominales.Cette analyse statistique mène à la conclusion que les récepteurs GNSS opérant dans des régions de basse latitude peuvent voir leurs performances de positionnement affectées par des scintillations ionosphériques durant 20%–30% du temps en cas de conditions de scintillations ionosphériques actives.La combinaison d’effets néfastes engendrés par des atténuations de signal, des pertes de verrouillage de signal et des sauts de cycles entraîne une forte baisse des performances des algorithmes SPP et PPP en termes d’exactitude, de continuité et de fiabilité.This approach turns out to be successful in detecting, scaling and tracking significantly positive spatial autocorrelation in ionospheric scintillation skyplots during active ionospheric conditions.The spatial analysis techniques exploited in the framework of this research eventually led to the design of three types of real-time ionospheric scintillation skymaps that quantify the spatiotemporal characteristics of low-latitude ionospheric scintillations.
Comments Dissertation Ionosphere
Dayside Aurora and its Connection to the Solar Wind.
This dissertation presents a comprehensive study of the dayside auroral dynamics and remote sensing of coupled magnetosphere-ionosphere system.…
AN IONOSPHERIC REMOTE SENSING. - SMARTech
Waves and the lowest portion of Earth's ionosphere, known as the D. goal of this thesis is to develop a VLF remote sensing method, with an.…
Ingestion of Ionospheric Scintillation Skymaps into GNSS.
First, this PhD thesis presents a statistical analysis based on measurements performed by a network of Ionospheric Scintillation Monitoring.…
A rocket-borne investigation of auroral electrodynamics within.
This dissertation focuses on data analyzed from the Auroral Current and Electro-. that the sheet field aligned current into the ionosphere equal the sheet field.…
Addition To Ph. D. Thesis Proposal B Literature Review.
Discusses how they will be investigated as part of this thesis project. natural auroral ionosphere, since the integration times required are.…
Meter-scale waves in the E-region Ionosphere cross-scale.
Meter-scale waves in the E-region Ionosphere cross-scale coupling and. This dissertation answers two fundamental questions about the FBI How does it.…
Magnetic states of the ionosphere of Venus observed by.
And T. L. Zhang, Structure and dynamics of the upper ionosphere of Venus. This thesis focuses on the investigation of the prevalence of magnetic fields in the.…
UCGE Reports Carrier Phase Based Ionosphere Recovery.
Ionosphere recovery method has been tested using data from a regional GPS network. The major objective of this thesis is to investigate a new ionosphere.…