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Auteur Dennis Odijk |
Documents disponibles écrits par cet auteur (6)
Ajouter le résultat dans votre panier Affiner la recherche Interroger des sources externesGPS, Galileo, QZSS and IRNSS differential ISBs: estimation and application / Dennis Odijk in GPS solutions, vol 21 n° 2 (April 2017)
Titre : GPS, Galileo, QZSS and IRNSS differential ISBs: estimation and application Type de document : Article/Communication Auteurs : Dennis Odijk, Auteur ; Nandakumaran Nadarajah, Auteur ; Safoora Zaminpardaz, Auteur ; Peter J.G. Teunissen, Auteur Année de publication : 2017 Article en page(s) : pp 439 – 450 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] base géodésique
[Termes IGN] constellation GNSS
[Termes IGN] données GNSS
[Termes IGN] erreur systématique inter-systèmes
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement par GNSS
[Termes IGN] résolution d'ambiguïtéRésumé : (auteur) Knowledge of inter-system biases (ISBs) is essential to combine observations of multiple global and regional navigation satellite systems (GNSS/RNSS) in an optimal way. Earlier studies based on GPS, Galileo, BDS and QZSS have demonstrated that the performance of multi-GNSS real-time kinematic positioning is improved when the differential ISBs (DISBs) corresponding to signals of different constellations but transmitted at identical frequencies can be calibrated, such that only one common pivot satellite is sufficient for inter-system ambiguity resolution at that particular frequency. Recently, many new GNSS satellites have been launched. At the beginning of 2016, there were 12 Galileo IOV/FOC satellites and 12 GPS Block IIF satellites in orbit, while the Indian Regional Navigation Satellite System (IRNSS) had five satellites launched of which four are operational. More launches are scheduled for the coming years. As a continuation of the earlier studies, we analyze the magnitude and stability of the DISBs corresponding to these new satellites. For IRNSS this article presents for the first time DISBs with respect to the L5/E5a signals of GPS, Galileo and QZSS for a mixed-receiver baseline. It is furthermore demonstrated that single-frequency (L5/E5a) ambiguity resolution is tremendously improved when the multi-GNSS observations are all differenced with respect to a common pivot satellite, compared to classical differencing for which a pivot satellite is selected for each constellation. Numéro de notice : A2017-214 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-016-0536-y En ligne : http://dx.doi.org/10.1007/s10291-016-0536-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85084
in GPS solutions > vol 21 n° 2 (April 2017) . - pp 439 – 450[article]
Titre : On the estimability of parameters in undifferenced, uncombined GNSS network and PPP-RTK user models by means of S-system theory Type de document : Article/Communication Auteurs : Dennis Odijk, Auteur ; Baocheng Zhang, Auteur ; Amir Khodabandeh, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 15 - 44 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] constellation GNSS
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement ponctuel précis
[Termes IGN] temps réel
[Termes IGN] utilisateurRésumé : (auteur) The concept of integer ambiguity resolution-enabled Precise Point Positioning (PPP-RTK) relies on appropriate network information for the parameters that are common between the single-receiver user that applies and the network that provides this information. Most of the current methods for PPP-RTK are based on forming the ionosphere-free combination using dual-frequency Global Navigation Satellite System (GNSS) observations. These methods are therefore restrictive in the light of the development of new multi-frequency GNSS constellations, as well as from the point of view that the PPP-RTK user requires ionospheric corrections to obtain integer ambiguity resolution results based on short observation time spans. The method for PPP-RTK that is presented in this article does not have above limitations as it is based on the undifferenced, uncombined GNSS observation equations, thereby keeping all parameters in the model. Working with the undifferenced observation equations implies that the models are rank-deficient; not all parameters are unbiasedly estimable, but only combinations of them. By application of S-system theory the model is made of full rank by constraining a minimum set of parameters, or S-basis. The choice of this S-basis determines the estimability and the interpretation of the parameters that are transmitted to the PPP-RTK users. As this choice is not unique, one has to be very careful when comparing network solutions in different S-systems; in that case the S-transformation, which is provided by the S-system method, should be used to make the comparison. Knowing the estimability and interpretation of the parameters estimated by the network is shown to be crucial for a correct interpretation of the estimable PPP-RTK user parameters, among others the essential ambiguity parameters, which have the integer property which is clearly following from the interpretation of satellite phase biases from the network. The flexibility of the S-system method is furthermore demonstrated by the fact that all models in this article are derived in multi-epoch mode, allowing to incorporate dynamic model constraints on all or subsets of parameters. Numéro de notice : A2016-022 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0854-9 Date de publication en ligne : 05/11/2015 En ligne : https://doi.org/10.1007/s00190-015-0854-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79465
in Journal of geodesy > vol 90 n° 1 (January 2016) . - pp 15 - 44[article]
Titre : ADOP in closed form for a hierarchy of multi-frequency single-baseline GNSS models Type de document : Article/Communication Auteurs : Dennis Odijk, Auteur ; Peter J.G. Teunissen, Auteur Année de publication : 2008 Article en page(s) : pp 473 - 492 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] affaiblissement de la précision
[Termes IGN] ambiguïté entière
[Termes IGN] modèle de diffusion du rayonnement
[Termes IGN] positionnement par GNSS
[Termes IGN] propagation du signal
[Termes IGN] résolution d'ambiguïté
[Termes IGN] signal GNSSRésumé : (Auteur) Successful carrier phase ambiguity resolution is the key to high-precision positioning with Global Navigation Satellite Systems (GNSS). The ambiguity dilution of precision (ADOP) is a well-known scalar measure which can be used to infer the strength of the GNSS model for carrier phase ambiguity resolution. In this contribution we present analytical closed-form expressions for the ADOP. This will be done for a whole class of different multi- frequency single baseline models. These models include the geometry-fixed, the geometry-free and the geometry-based models, respectively. And within the class of geometry-based models, we discriminate between short and long observation time spans, and between stationary and moving receivers. The easy-to-use ADOP expressions can be applied to infer the contribution of various GNSS model factors. They comprise, for instance, the type, the number and the precision of the GNSS observations, the number and selection of frequencies, the presence of atmospheric disturbances, the length of the observation time span and the length of the baseline. Copyright Springer Numéro de notice : A2008-320 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0197-2 En ligne : https://doi.org/10.1007/s00190-007-0197-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29313
in Journal of geodesy > vol 82 n° 8 (August 2008) . - pp 473 - 492[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-08071 RAB Revue Centre de documentation En réserve L003 Disponible 266-08072 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : Making a difference with GPS: time differences for kinematic positioning with low-cost receivers Type de document : Article/Communication Auteurs : J. Traugott, Auteur ; Dennis Odijk, Auteur ; Oliver Montenbruck, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 48 - 54 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] GPS en mode différentiel
[Termes IGN] phase GPS
[Termes IGN] positionnement cinématique
[Termes IGN] récepteur GPS
[Termes IGN] traitement de données GNSSRésumé : (Editeur) Most radio signals consist of a carrier wave that is modulated in some way. This includes the GPS satellite signals. The pseudorandom-noise ranging codes and the navigation message are modulated onto the L-band carriers using binary biphase modulation. A GPS receiver uses the ranging codes to determine its distance from multiple satellites and then, through the process of multilateration, its position. But what about the carrier phase? Is it just a means to convey the ranging codes and navigation message? Definitely not. A GPS receiver determines its velocity as well as its position and it does this not by differencing sequential code-based positions, which would not be very accurate, but rather by measuring the Doppler shift of the received carrier. But the carrier can be used in other ways too. In fact, it can be used for determining positions, just like the code, but with much higher precision. Over 20 years ago, surveyors and geodesists devised ways to make use of recorded measurements of the phase of the received carriers to determine accurate relative positions between a roving receiver and a base or reference receiver at a known location. The technique was enhanced over the years, evolving into an approach known as RTK or real-time kinematic positioning. As its name suggests, RTK is usually employed in real time using auxiliary radio communications (often cell-phone-based) between the base and rover receivers. However, RTK-style positioning can also be used to postprocess collected data, achieving the same high-accuracy standards. But one of the difficulties with the RTK approach is resolving the so-called carrier-phase ambiguities. One cycle of the carrier looks just like the next, so how can you determine the exact number of cycles in the carrier between the satellite's antenna and the receiver's antenna? Well, it can be done, but even with increasingly sophisticated techniques, there is a limit to how far away a rover can be from the base station. Isn't there a way to get rid of the integer ambiguity problem? There is. If you time-difference sequential carrier-phase measurements, the ambiguity actually disappears! As we'll see in this month's column, you can determine accurate relative positions using time-differenced carrier-phase measurements. But there are some caveats. Read on. Copyright Questex Media Group Inc Numéro de notice : A2008-164 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29159
in GPS world > vol 19 n° 5 (May 2008) . - pp 48 - 54[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 067-08051 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : Fast precise GPS positioning in the presence of ionospheric delays Type de document : Thèse/HDR Auteurs : Dennis Odijk, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2002 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 52 Importance : 242 p. Format : 16 x 24 cm ISBN/ISSN/EAN : 978-90-6132-278-8 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] ambiguïté entière
[Termes IGN] correction ionosphérique
[Termes IGN] correction troposphérique
[Termes IGN] données GPS
[Termes IGN] interpolation
[Termes IGN] krigeage
[Termes IGN] mesurage de phase
[Termes IGN] méthode des moindres carrés
[Termes IGN] modèle de Gauss-Markov
[Termes IGN] modèle ionosphérique
[Termes IGN] modèle stochastique
[Termes IGN] propagation ionosphérique
[Termes IGN] propagation troposphérique
[Termes IGN] réfraction atmosphérique
[Termes IGN] résolution d'ambiguïté
[Termes IGN] signal GPS
[Termes IGN] station virtuelle
[Termes IGN] traitement de données GNSS
[Termes IGN] traitement du signalIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (Auteur) This thesis deals about geodetic applications of the Global Positioning System (GPS), in which the position of the GPS receiver must be determined with cm precision. This requires a relative measurement setup, together with an advanced processing strategy based on observations of the carrierphase of the signal. To keep it economically interesting, this CPS technique should be based on relatively short time spans in which the satellite observations are collected. The key to precise positioning using short time spans is to take advantage of the integer property of the ambiguities of the phase observations in the processing.
The above procedure has been applied in a successful way for the last decade to applications in which the distance between the receivers is restricted to about 10 km (the socalled rapidstatic and realtime kinematic GPS techniques over short distances). Above this distance, it is known that certain errors in the GPS observations start to significantly bias the computed receiver position when they are not taken care of. The aim of this research therefore is to develop a processing procedure, taking into account the errors in GPS observations due to propagation of the signals through the ionosphere, the atmospheric layer above about 80 kill. Although other errors (due to troposphere and satellite orbit) are of relevance as well, the research is restricted to an improved modelling of the ionospheric error. since it is by far the largest error. For the other errors standard modelling techniques are applied in this research. Using the procedure, it should be possible to determine the desired receiver positions with cmprecision using a short tinle span. The research is restricted to GPS receivers with a mutual distance of a few hundred km (mediumdistance baselines), located in midlatitude regions.
To facilitate a modelling of the ionospheric error, using the theor ' y of atmospheric refraction it is possible to decompose this error into a firstorder effect, which contains the gross of the error, plus some higherorder effects and a term due to bending of the signal path. Under worstcase conditions. the firstorder term may range up to about 80 m (on the GPS L2 frequency), whereas the accumulated effect of higherorder and bending terms can be tip to 4 cm (for L2). For the future L5 frequency (from 2008) these effects are even larger. Fortunately, because of the relative setup and the assumed medium distances, it is proved for this research it is allowed to neglect the higherorder and bending errors.
In the procedure a stochastic modelling of the firstorder ionospheric errors (referred to as ionospheric delays) is chosen. This means that the ionospheric delays are not modelled as completely unknown parameters, but that stochastic prior information is incorporated by means of ionospheric pseudoobservations. This model is referred to as the ionosphereweighted model: The weight of the ionospheric information can be tuned by the a priori standard deviation of the pseudoobservations. When this standard deviation is chosen zero, the ionosphereweighted model reduces to the ionospherefixed model, which is the usual processing model for shortdistance baselines (for which the ionospheric delays may be neglected). On the other hand, with an infinitely large ionospheric standard deviation, the model will be equivalent to the ionospherefloat model, in which the ionospheric delays are assumed as completely unknown parameters. This latter model is closely related to the ionospherefree combination, for which it is known that it cannot be used to achieve fast positioning results. It is shown that the ionosphereweighted model is only suitable for fast ambiguity resolution (and consequently positioning), when the ionospheric standard deviation is small. This requires very precise a priori ionospheric information.
The developed procedure consists of three steps. It is required that a user collects CPS observations in the vicinity of a network of permanent GPS stations. In the first step, the observations at the network stations are processed simultaneously using the ionosphereweighted model. Since in this research the goal is precise positioning within the shortest time span possible, i.e. instantaneous or singleepoch positioning, it is required that the network data is also processed instantaneously. To make instantaneous resolution of the network ambiguities possible, the sample values of the ionospheric pseudoobservations are temporal predictions based on estimates of previous epochs. Test computations using a network with a station spacing of more than 100 km demonstrated that in this way high network ambiguity success rates (close to 100%) can be obtained. In the second step, precise ambiguityfixed network ionospheric delays are spatially interpolated at the approximate location of the user's receiver. In the procedure for this purpose the concept of virtual reference station (VRS) observations is used. In this concept the network estimates (ionospheric delays and other parameters) are transformed to VRS observations. which should correspond to the data a real receiver would have collected at the user's location. The processing of the user's observations relative to this VRS is the third step of the procedure. Because of the presence of possible residual ionospheric delays also in this step the ionosphereweighted model is applied. The difference with the application in the network processing is that the sample values of the pseudoobservations are now taken zero. and the ionospheric standard deviation is computed as a function of the distance to the closest real network station. Using this, test computations demonstrated that instantaneous ambiguity success rates of 90% are feasible. When the ionospherefixed model would be applied, the success rates would not be higher than about 60%.Numéro de notice : 13101 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : sans En ligne : https://www.ncgeo.nl/downloads/52Odijk.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54884 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 13101-01 30.61 Livre Centre de documentation Géodésie Disponible Permalink
