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Precise relative positioning of formation flying spacecraft using GPS / R. Kroes (2006)
Titre : Precise relative positioning of formation flying spacecraft using GPS Type de document : Monographie Auteurs : R. Kroes, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2006 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 61 Importance : 163 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-296-2 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] ambiguïté entière
[Termes IGN] compensation Lambda
[Termes IGN] erreur systématique
[Termes IGN] filtre de Kalman
[Termes IGN] GPS-INS
[Termes IGN] GRACE
[Termes IGN] image TerraSAR-X
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] méthode des moindres carrés
[Termes IGN] navigation spatiale
[Termes IGN] orbitographie par GNSS
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement par GPS
[Termes IGN] précision millimétrique
[Termes IGN] qualité des données
[Termes IGN] résolution d'ambiguïté
[Termes IGN] signal GPSIndex. décimale : 30.70 Navigation et positionnement Résumé : (Auteur) Spacecraft formation flying is currently considered as a key technology for advanced space missions. Compared to large individual spacecraft, the distribution of Sensor systems amongst multiple platforms offers improved flexibility and redundancy, shorter times to mission and the prospect of being more cost effective. Besides these advantages, satellite formations in low Earth orbit provide advanced science opportunities that cannot, or not easily, be realized with single spacecraft. One of the fundamental issues of spacecraft formation flying is the determination of the relative state (position and velocity) between the satellite vehicles within the formation. Knowledge of these relative states in (near) real-time is important for operational aspects. In addition, some of the scientific applications, such as high resolution interferometry, require an accurate post-facto knowledge of these States. The goal of this dissertation is therefore to develop, implement and test a method for high precise post-facto relative positioning of formation flying spacecraft, using GPS observation data. The need for such a methodology comes from scientific satellite formation flying missions that are currently being planned. A good example here is the Synthetic Aperture Radar (SAR) interferometry formation consisting of the TerraSAR-X and TanDEM-X satellites. The primary mission objective here requires the relative position to be known within a 2 mm precision (1-dimensional).
GPS receivers are often considered as the primary instruments for precise relative navigation in future satellite formation flying missions. As is commonly known, precise relative positioning between GPS receivers in geodetic networks is exercised on a routine basis. Furthermore, GPS receivers are already frequently used onboard satellites to perform all kinds of navigational tasks, are suitable for real-time applications and provide measurements with a 3-dimensional nature.
Previous studies carried out in this research area focussed on the real-time or operational aspects, and all used GPS data obtained from software or hardware-in-the-loop simulations. This dissertation clearly distinguishes itself due to the fact that the developed methodology has been tested using real-world GPS data from the GRACE mission, which in addition also provides a precise way to validate the obtained results by means of the GRACE K/Ka-Band Ranging System (KBR) observations.
One of the key aspects of any GPS positioning application is the quality of the observation data used. To this extent an in-flight performance analysis of the used GRACE (and CHAMP) GPS data bas been carried out. The results show that the GRACE GPS pseudorange observations, on the individual frequencies, are subject to systematic errors in the order of 10-15 cm. Furthermore, an assessment of the noise of both the GPS pseudorange and carrier phase data demonstrates that the noise of the GRACE B observation data is significantly lower.
When using GPS for precise relative spacecraft positioning, the trajectory or orbit of one of the spacecraft, serving as the reference, has to be known to the best possible extent. In order to facilitate this, a total of three precise orbit determination strategies, using undifferenced ionosphere free GPS pseudorange and carrier phase observations, have been implemented and tested. They comprise a kinematic and reduced dynamic batch LSQ estimation method, as well as an extended Kalman filter/smoother (EKF), that also form the conceptual basis for the relative spacecraft positioning strategies. Each of the precise orbit determination concepts has been tested using GPS data from the CHAMP and GRACE missions. The reduced dynamic batch LSQ orbits were validated with Satellite Laser Ranging data, where the residuals showed an RMS of 3-4 cm.
Out of a total of four possible processing strategies that have been identified for relative spacecraft positioning, only an extended Kalman filter/smoother has proven to work satisfactorily when tested on the real-world GRACE GPS data. The EKF processes single difference GPS pseudorange and carrier phase observations and uses (pseudo) relative spacecraft dynamics to propagate the relative satellite state over the observation epochs. Despite its single difference parametrization the EKF can still resolve and incorporate the integer double difference carrier phase ambiguities, which is commonly regarded as, and has proven to be in this dissertation, the key to precise GPS based relative positioning. Estimation of the integer ambiguities is accomplished by the well known Least Squares Ambiguity Decorrelation Adjustment (LAMBDA) method. Due to the presence of systematic errors in the GRACE GPS data, a relatively conservative validation of the estimated integer ambiguity parameters was found to be required prior to their incorporation in the filter. When validating the daily ambiguity fixed GRACE relative position solutions from the EKF with the KBR observations, it has been shown that an actual overall relative position precision of 0.9 mm (1-dimensional) over a 101 day data arc is achieved. This dissertation is the first that proves that such precision can be truly obtained for real-world relative spacecraft positioning applications.Note de contenu : Acknowledgements
Important Acronyms
Summary
Samenvatting (Summary in Dutch)
1 Introduction
1,1 Spacecraft formation flying using GPS
1.2 Research objective and motivation
1.3 The CHAMP and GRACE satellite missions
1.4 Outline
2 GPS observations
2.1 Observation types
2.3 Linear data combinations
2.4 Linearization for positioning
2.5 Relative positioning models
2.6 GPS data quality
3 Precise orbit determination
3.1 GPS orbit and clock products
3.2 Reference frame transformations.
3.3 Kinematic orbit determination.
3.4 Reduced dynamic orbit determination
3.5 GHOST toolkit
3.6 POD results
4 Relative spacecraft positioning
4.1 Integer ambiguity resolution
4.2 Proposed processing strategies
4.3 Details of the extended Kalman filter
4.4 Extended Kalman filter results.
4.5 Some words on
5 Conclusions and outlook
A Integer Ambiguity Estimation
B Lower boundary for the bootstrapping success rate
BibliographyNuméro de notice : 15179 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=55089 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 15179-01 30.70 Livre Centre de documentation Géodésie Disponible 15179-02 30.70 Livre Centre de documentation Géodésie Disponible Semantic interoperability of distributed geo-services / Robert Lemmens (2006)
Titre : Semantic interoperability of distributed geo-services Type de document : Monographie Auteurs : Robert Lemmens, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2006 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 63 Importance : 291 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-298-6 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Infrastructure de données
[Termes IGN] architecture client-serveur
[Termes IGN] base de connaissances
[Termes IGN] diffusion de données
[Termes IGN] hétérogénéité sémantique
[Termes IGN] infrastructure mondiale des données localisées
[Termes IGN] intégration de données
[Termes IGN] interopérabilité sémantique
[Termes IGN] logiciel libre
[Termes IGN] modèle sémantique de données
[Termes IGN] ontologie
[Termes IGN] OWL
[Termes IGN] prototype
[Termes IGN] réseau sémantique
[Termes IGN] service de géoinformation
[Termes IGN] service fondé sur la position
[Termes IGN] service web géographique
[Termes IGN] système d'information géographiqueRésumé : (Auteur) The last two decades have shown a major shift from stand-alone software systems to networked ones. As with all information system domains, Geographic Information Systems (GISs) have been influenced to a large extent by recent internet developments, resulting in an increasing availability of client/server applications using distributed geo-(web-)services, such as interactive maps, route planners and gazetteers. There is an increasing need for organisations to perform on demand geo-processing tasks by integrating and reusing geo-information and geo-services from within and outside the organisation. These activities are typically performed in the context of so called Geo-Information Infrastructures (GIls).
The process of integrating services is commonly referred to as service chaining. This requires that services can be easily found, and that they are executable and interoperable. Interoperability means that the services 'understand' each other's messages. A major impediment is formed by the semantic heterogeneity (the differences in meaning) of geo-information and of the functionality of geo-services. Making services semantically interoperable is an important prerequisite for information sharing in today's networked society. This involves services that rely on different knowledge domains, one of which is the geo-information domain.
Within this context, the research presented in this thesis provides solutions for the computer-aided integration of distributed heterogeneous geo-information and geo-services, based on their semantics (the meaning of their content).
Geo-information distinguishes from other information by its spatial relevance. Geo-services often have to deal integrally with multiple-representations of features in a spatial, temporal and thematic dimension. Geo-services are also implicitly connected by the geographic location of the features they process. This has implications for the interoperability of geo-services. For example, the validity of a service (e.g., a routeplanner) may be bound to a specific geographic area, which could imply it cannot be used in combination with services involving another validity area. On the contrary, services that seem to be incompatible due to differences in feature representation (e.g., geometry, coordinate reference system), may turn out to be useful in combination, because they contain information on the same locations.
On demand geo-processing requires services and the meta-information that describes the services to be available at the time a task is being executed. Moreover, the service descriptions should be based on commonly agreed rules for service characterisation. Inter-service contracts that contain such rules may result in service interoperability and this can be achieved at three levels: syntax, structure and semantics. The influential specifications of the Open Geospatial Consortium (OGC) and the ISO 19100 series of standards, implement formal contracts on the syntactical and structural level, but they prescribe only informal contracting at the semantic level. Despite their rigid conceptualisation, they lack a machine-accessible formalisation that supports the specification of semantics for geo-information and geo-services. This research has developed such a formalisation, which is specified in a so called semantic interoperability framework. In this framework a key role is played by machine ontologies, which are machine-accessible representations of knowledge that are used for inferring intra- and inter-resource relationships. Recent research efforts in the field of the Semantic Web have contributed considerably to the deployment of ontology-based applications by providing a theoretical foundation (Description Logics), ontology languages (e.g., the Web Ontology Language (OWL)), and tools for ontology creation, access and reasoning with web-based (machine) ontologies. The power of web-based ontologies lies in their interoperable (XML based) representation, the use of unique namespaces and the fact that they allow for automated reasoning.
The semantic interoperability framework developed in this research, contains (1) geo-information modelling ontologies which are based on the ISO General Feature Model, (2) domain specific ontologies (amongst others, one which is based on a data model used by the Dutch Topographic Service), and (3) a geo-operation modelling ontology. The latter is based on a geo-operation taxonomy, an input/output parameter characterisation and a workflow model. The taxonomy and parameter characterisation have been developed as part of this research, the workflow model is based on OWL-S, an OWL-based upper ontology for web services.
Ontology-based service descriptions have been created in the context of four use cases in the following areas: (1) information model integration for risk mapping, (2) ad hoc data integration in a disaster emergency situation, (3) reuse of geo-data and geo-services in scientific research, and (4) ad hoc integration of travel services. The ontology-based descriptions are used as representations of service requests and advertisements in a matchmaking process. The matchmaking is performed by an ontology reasoner which can infer implicit relationships that exist in a knowledge base containing service descriptions as sets of concepts. The reasoner is implemented together with the ontologies in a prototype environment. Except for the reasoner, this has been carried out with open source software. Within this environment, basic matchmaking has been successfully performed to support data set integration and service chaining. This has been demonstrated by tests implementing the aforementioned use cases.
The offered solution is flexible and extensible. With respect to flexibility, the research demonstrates the use of incomplete service descriptions. With respect to extensibility, the research shows how service descriptions can be extended with new concepts. It is also demonstrated how existing application domains can be linked through ontology mappings. In the process of service chaining, four steps have been identified, i.e., discovery, abstract composition, concrete composition and execution. The link between the abstract and concrete composition of services is realised by annotation, which connects ontology elements with parameters of executable code. For one of the use cases, this code has been deployed in a prototype software application (the latter being part of an external research effort).
There are also limitations to the approach followed, which are partly due to the limitations of OWL and reasoning with it, i.e., with respect to spatial reasoning and the use of metaclasses. In addition, the current prototype environment has several shortcomings: (1) constraints of the user-interfaces (entering service descriptions in Description Logics is still rather complex), (2) the inflexibility of the reasoning implementation and (3) the incompleteness of mappings between domain ontologies, all of which are thought to be surmountable.
A number of recommendations are made for the improvement of the current design and implementation of the interoperability framework, such as the incorporation of: meta-information propagation, concept similarity quantifiers and result ranking in the matchmaking process. The deployment of the approach requires key organisations such as OGC to develop and maintain domain independent parts of a semantic interoperability framework and organisations with a GIl mandate to manage its domain dependent parts.
Application fields that are thought to benefit from the presented approach in the short term are, amongst others: service discovery and chaining in GII, harmonisation of geo-information models, multiple-representation of geo-information, profile matching of geo-service users, documentation of geo-processing history (lineage), and quality assessment of meta-information. The target groups of this research are firstly geo-information engineers who are confronted with information integration issues and service interoperability issues, and secondly, information engineers in general confronted with distributed information and with end users that need to access distributed services as one virtual application.Note de contenu : Abstract
Samenvatting
Acknowledgements
1 Why interoperability is important
1.1 Research context and motivation
1.2 Research objectives
1.3 Research approach
1.4 Related work
1.5 Thesis outline
2 Interoperable distributed services
2.1 Distributed processing paradigms
2.2 Interoperability and heterogeneity
2.3 Overcoming heterogeneity by contract
2.4 Interoperability models
2.5 Geo-services
2.6 Geo-service use cases
2.7 Summary and reflection
3 Service models for discovery, composition and execution
3.1 Information modelling
3.2 Process modelling
3.3 Service chaining
3.4 Summary and reflection
4 Semantic modelling
4.1 What is an ontology?
4.2 Foundations for machine ontology
4.3 Ontology design and creation
4.4 Ontology representations and notation
4.5 Reasoning with a knowledge base
4.6 Semantic interoperability frameworks
4.7 Semantic web services
4.8 Geo-semantic modelling and spatial relevance
4.9 Summary and reflection
5 Semantic interoperability framework for geo-services
5.1 Semantic framework overview
5.2 Feature symbol ontology
5.3 Feature concept ontologies
5.4 Geo-operation characterisations ? OPERA
5.5 OPERA-R ? Feature processing operations
5.6 Geo-service descriptions
5.7 Summary and reflection
6 Geo-information matching and service chaining
6.1 Example: Riskmap chain
6.2 Semantic modelling of geo-service chains
6.3 Derived operations and ontology mappings
6.4 Matchmaking
6.5 Summary and reflection
7 Use case implementations
7.1 Riskmap NL
7.2 Emergency 112
7.3 Research Net
7.4 Travel Google
7.5 Summary and reflection
8 Implementation of prototypes: OnToGeo and GeoMatchMaker
8.1 Practical design and implementation issues of OnToGeo
8.2 Workbench tools
8.3 GeoMatchMaker, an integrated prototype
8.4 Creating service descriptions
8.5 Summary and reflection
9 Conclusions and recommendations
9.1 Summary and reflection
9.2 Conclusions
9.3 Main contributions
9.4 Deployment
9.5 Recommendations for further work
A UML notation
B ISO 19100 overview
C OPERA-R geo-operation types
C.I Human interaction operations
C.2 Feature modelling
C.3 Feature access
C.4 Feature processing
C.5 Feature presentation manipulation
C.6 Service creation and management
C.7 Service execution
C.8 Metalnfo creation and storage management
C.9 Metalnfo processing
C.10 Metalnfo presentation manipulation
D OPERA-R
I/O parameters for feature processing operations
E ADL Gazetteer OWL service description
F ADL Gazetteer WSDL service description
G ISO 19119 mappingNuméro de notice : 15204 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=55094 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 15204-01 37.00 Livre Centre de documentation Géomatique Disponible 15204-02 37.00 Livre Centre de documentation Géomatique Disponible Segmentation and classification of airborne laser scanner data / George Sithole (2005)
Titre : Segmentation and classification of airborne laser scanner data Type de document : Monographie Auteurs : George Sithole, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2005 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 59 Importance : 184 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-292-4 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] algorithme de filtrage
[Termes IGN] classification dirigée
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] milieu urbain
[Termes IGN] précision de la classification
[Termes IGN] segmentation
[Termes IGN] semis de points
[Termes IGN] télémétrie laser aéroportéIndex. décimale : 35.20 Traitement d'image Résumé : (Auteur) Various methods have been developed to measure the physical presence of objects in a landscape with high positional accuracy, such as Airborne Laser Scanning (ALS). [...] The product of ALS is a cloud of points in 3D space. ALS is capable of delivering very dense and accurate point clouds of a landscape in a relatively short time. [...] However, the automatic detection and interpretation of individual objects remains a challenge. [...] Several algorithms have been developed to automatically detect the bare earth in ALS point clouds. An experimental study of filtering algorithms determined that in flat and uncomplicated landscapes, algorithms tend to do well. Significant differences in accuracies of filtering appear in landscapes containing steep slopes and discontinuties. These differences are a result of the ability of algorithms to preserve discontinuties while detecting large objects. A solution for this problem was determined to lie in the segmentation of ALS point clouds. If segmentation can be achieved in such a manner that all bare earth points are gathered into their own surface segments, then filtering can be done on the basis of surfaces rather than points. This should offer a more reliable classification since topological information can be used in addition to geometric information to classify surface segments. On the strenght of the study, a new segmentation based filtering algorithm was developed. [...] Numéro de notice : 13237 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54926 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13237-01 35.20 Livre Centre de documentation Télédétection Disponible 13237-02 35.20 Livre Centre de documentation Télédétection Disponible Spatial data quality / P. Van Oort (2005)
Titre : Spatial data quality : from description to application Type de document : Monographie Auteurs : P. Van Oort, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2005 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 60 Importance : 125 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-295-5 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Infrastructure de données
[Termes IGN] base de données d'occupation du sol
[Termes IGN] covariance
[Termes IGN] données localisées
[Termes IGN] erreur de classification
[Termes IGN] généalogie des données
[Termes IGN] incertitude des données
[Termes IGN] occupation du sol
[Termes IGN] précision de la classification
[Termes IGN] qualité des données
[Termes IGN] terminologie
[Termes IGN] varianceRésumé : (Auteur) The growing availability of spatial data along with growing ease to use the spatial data (thanks to wide-scale adoption of GIS) have made it possible to use spatial data in applications inappropriate considering the quality of the data. As a result, concerns about spatial data quality have increased. To deal with these concerns, it is necessary to (1) formalise and standardise descriptions of spatial data quality and (2) to apply these descriptions in assessing the suitability (fitness for use) of spatial data, before using the data. The aim of this thesis was twofold: (1) to enhance the description of spatial data quality and (2) to improve our understanding of the implications of spatial data quality.
Chapter 1 sets the scene with a discussion on uncertainty and an explanation of why concerns about spatial data quality exist. Knowledge gaps are identified and the chapter concludes with six research questions.
Chapter 2 presents an overview of definitions of spatial data quality. Overall, I found a strong agreement on which elements together define spatial data quality. Definitions appear to differ in two aspects: (1) the location within the meta-data report: some elements occur not in the spatial data quality section but in another section of the meta-data report-, and (2) the explicitness with which elements are recognised as individual elements. For example, the European pre-standard explicitly recognises the element 'homogeneity'. Other standards recognise the importance of documenting the variation in quality, without naming it explicitly as an individual element.
In chapter 3, we quantified the spatial variability in classification accuracy for the agricultural crops in the Dutch national land cover database (LGN). Classification accuracy was significantly correlated with: (1) the crop present according to LGN, (2) the homogeneity of the 8-cell neighbourhood around each cell, (3) the size of the patch in which a cell is located, and (4) the heterogeneity of the landscape in which a cell is located.
In chapter 4, I present methods that use error matrices and change detection error matrices as input to make more accurate land cover change estimates. It was shown that temporal correlation in classification errors has a significant impact and must be taken into account. Producers of lime series land cover data are recommended not only to report error matrices, but also change detection error matrices.
Chapter 5 focuses on positional accuracy and area estimates. From the positional accuracy of vertices delineating polygons, the variance and covariance in area can be derived. Earlier studies derived equations for the variance, this chapter presents a covariance equation. The variance and covariance equation were implemented in a model and applied in a case-study. The case-study consisted of 97 polygons with a small subsidy value (in euros per hectare) assigned to each polygon. With the model we could calculate the uncertainty in the total subsidy value (in euros) of the complete set of polygons as a consequence of uncertainty in the position of vertices.
Chapter 6 explores the relationship between completeness of spatial data and risk in digging activities around underground cables and pipelines. A model is presented for calculating the economic implications of over- and incompleteness. An important element of this model is the relationship between detection lime and costs. The model can be used to calculate the optimal detection time, i.e. the time at which expected costs are at their minimum.
Chapter 7 addresses the question why risk analysis (RA) is so rarely applied to assess the suitability of spatial data prior to using the data. In theory, the use of RA is beneficial because it allows the user to judge if the use of certain spatial data does not produce unacceptable risks. Frequently proposed hypotheses explaining the scarce adoption of RA are all technical and educational. In chapter 7 we propose a new group of hypotheses, based on decision theory. We found that the willingness to spend resources on RA depends (1) on the presence of feedback mechanisms in the decision-making process, (2) on how much is at stake and (3) to a minor extent on how well the decision-making process can be modelled.
Chapter 8 prescrits conclusions on the six research questions (chapters 2-7) and lists recommendations for users, producers and researchers of spatial data. With regard to the description, four recommendations are given. Firstly, spend more effort on documenting the lineage of reference data. Secondly, quantify and report correlation of quality between related data sets. Thirdly, investigate the integration of different forms of uncertainty (error, vagueness, ambiguity). Fourthly, study the implementation and use of spatial data quality standards. With regard to the application of spatial data quality descriptions, I have two main recommendations. Firstly, to continue the line of research followed in this thesis: quantification of implications of spatial data quality, through development of theory along with tangible illustrations in case-studies. Secondly, there is a need for more empirical research into how users cope with spatial data quality.Numéro de notice : 13261 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54944 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13261-02 37.00 Livre Centre de documentation Géomatique Disponible 13261-01 37.00 Livre Centre de documentation Géomatique Disponible The GNSS integer ambiguities / S. Verhagen (2005)
Titre : The GNSS integer ambiguities : estimation and validation Type de document : Monographie Auteurs : S. Verhagen, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2005 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 58 Importance : 170 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-290-0 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] ambiguïté entière
[Termes IGN] axiome de Bayes
[Termes IGN] code GPS
[Termes IGN] contrôle qualité
[Termes IGN] distribution de Student
[Termes IGN] distribution, loi de
[Termes IGN] estimation statistique
[Termes IGN] Galileo
[Termes IGN] Global Navigation Satellite System
[Termes IGN] Global Orbitography Navigation Satellite System
[Termes IGN] Global Positioning System
[Termes IGN] mesurage de phase
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle fonctionnel
[Termes IGN] modèle stochastique
[Termes IGN] phase
[Termes IGN] propagation du signal
[Termes IGN] qualité des données
[Termes IGN] résidu
[Termes IGN] résolution d'ambiguïtéIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (Auteur) Fast and high precision relative positioning with a Global Navigation Satellite System (GNSS) is only possible by using the very precise carrier phase measurements. However, these carrier phases are ambiguous by an unknwon number of cycles. The knowledge that the ambiguities are integer-valued has been exploited in the past 15 years for the development of integer ambiguity resolution algorithms. Once the ambiguities are fixed to their integer values, the carrier phase measurements start to act as if they were very precise pseudorange measurements. [...] Nowadays, the non-trivial problem of integer ambiguity estimation can be considered solved. However, a parameter estimation theory is not complete without the appropriate measures to validate the solution. [...] Obviously, validation of the integer ambiguity solution is still an open problem. Two approaches are investigated here. The first method uses a new ambiguity estimator, the Best Integer Equivariant (BIE) estimator. [...] It was shown that the BIE estimator significantly outperforms the float or fixed solution only in a limited number of cases. Therefore, another new class of integer estimators is investigated : the class of Integer Aperture (IA) estimators. [...] IA estimation has several important advantages. [...] Finally, it is shown that the popular ratio test perform almost as good as the optimal IA estimator if the fixed fail rate approach is used. [...] Note de contenu : Summary
Notation and symbols
Acronyms
1 Introduction
1.1 Background
1.2 Objectives and contribution of this work
1.3 Outline
2 GNSS observation model and quality control
2.1 Global Navigation Satellite Systems
2.2 GNSS observation equations
2.3 GNSS functional model
2.4 GNSS stochastic model
2.5 Least-squares estimation and quality control
3 Integer ambiguity resolution
3.1Integer estimation
3.2Quality of the integer ambiguity solution
3.3 The ambiguity residuals .
3.4 Quality of the fixed baseline estimator
3.5 Validation of the fixed solution
3.6 The Bayesian approach
4 Best Integer Equivariant estimation
4.1 The BIE estimator
4.2 Approximation of the BIE estimator
4.3 Comparison of the float, fixed, and BIE estimators .
4.4 Summary . .
5 Integer Aperture estimation
5.1 Integer Aperture estimation
5.2 Ellipsoidal integer aperture estimation
5.3 Ratio test, difference test and projector test
5.4 Integer Aperture Bootstrapping and LeastSquares .
5.5 Penalized Integer Aperture estimation
5.6 Optimal Integer Aperture estimation
5.7 Implementation aspects
5.8 Comparison of the different IA estimators
5.9 Performance of IA estimation
5.10 Summary
6 Conclusions and recommendations
6.1 Integer estimation and validation
6.2 Quality of the baseline estimators
6.3 Reliability of the results
6.4 Bias robustness
A Mathematics and statistics
A.1 Kronecker product
A.2 Parameter distributions
A.3 Numerical root finding methods
B Simulation and examples
B.1 Simulation
B.2 Examples.
C Theory of BlE estimation
C.1 Integer equivariant ambiguity estimation
C.2 Integer equivarlant unbiased ambiguity estimation
C.3 Best integer equivariant unbiased ambiguity estimation
C.4 Best integer equivariant unbiased baseline estimation
D Implementation aspects of IALS estimationNuméro de notice : 15134 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=55070 Réservation
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