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Zur Bestimmung der GPS-Phasenmehrdeutigkeiten in großräumigen Netzen / K. Wienholz (2003)
Titre : Zur Bestimmung der GPS-Phasenmehrdeutigkeiten in großräumigen Netzen Titre original : [Vers la résolution des ambiguïtés de phase GPS dans les réseaux à grande échelle] Type de document : Thèse/HDR Auteurs : K. Wienholz, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2003 Collection : DGK - C Sous-collection : Dissertationen num. 566 Importance : 102 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-5005-1 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] ambiguïté entière
[Termes IGN] ligne de base
[Termes IGN] logiciel de post-traitement GPS
[Termes IGN] mesurage de phase
[Termes IGN] modèle mathématique
[Termes IGN] phase GPS
[Termes IGN] propagation ionosphérique
[Termes IGN] résolution d'ambiguïté
[Termes IGN] traitement de données GNSSIndex. décimale : 30.61 Systèmes de Positionnement par Satellites du GNSS Résumé : (Auteur) The development and the results of the TUB method are presented in this paper. This special method serves in resolving GPS phase ambiguities in small-range and large-range networks. It is characterized by taking into account the correlates as quality criteria, thus enabling an assessment of the calculated ambiguities. First of all : by simulating an example to mediate the adjustment of conditions between unknown quantities it can be shown that every incorrect condition exerts a major constraint on the adjustment system. This constraint is reflected by the pertaining Lagrange factors (or correlates), the value of which increases rapidly in line with the magnitude of error in the equation of condition. This knowledge can be used in the TUB method to investigate various parameters. However, in this paper the emphasis is on the investigation of ambiguities.
The TUB method is based on a special parameterization of the observation equations so that several unknown parameters are combined in one newly established time-dependent auxiliary parameter and in one timeindependent auxiliary parameter. By reduction of the unknown parameters a stable equation system is brought about which can be solved without resulting in differences and linear combinations. The direct analysis of original phase observations prevents the error-propagation of accidental errors and hence an artificial increase in phase noise. Therefore the confidence intervals, characterized by integer numbers, can be kept rather small. In finding these integer numbers the time-dependent auxiliary parameters must first be separated in different ways, depending on the lengths of the base lines, from the ionospheric refraction. Then the ambiguities in the form of double differences, related to a base satellite and a base station (or in the form of L1/L2 ambiguity pairs), can be solved in an iterative process. As a controlling device equations of condition are formed with the help of L1/L2 ambiguity pairs and inserted in the adjustment process. A subsequent analysis of the correlates gives information about the qualities of the ambiguities found.
To begin with the potential of the TUB method is tested by means of a data set with base line lengths ranging from 13 to 48 km. By analyzing the correlates incorrect double difference ambiguities can be identified and among several integer numbers the correct one is filtered out. In two further nets with base line lengths from 26 to 106 km the influences of various more or less accurate orbits on the parameters of the observation equations are investigated. In the aforementioned examples a resolution of the ambiguities is possible at a success rate of 100 percent while an observation time of about two hours is sufficient. When terrain points are between 700 and 1000 km apart the model shows consider-able inaccuracies. The evaluation of data stemming from various IGS stations evidences that in about 20 percent of all ambiguities integer numbers cannot be found. In these cases the confidence intervals either do not provide any integer number or too many of them. In the latter case there are, instead of a single one, several LI/L2 ambiguity pairs that do not differ very much from one another. When these ambiguity pairs are inserted in the equation system the values of the correlates do not differ very much either. For the time being no satisfactory results can be achieved for base lines ranging between 1000 and 2000 km.
The analysis of the correlates proves to be a useful tool in evaluating the quality of ambiguities. The correlates with the highest values occur when incorrect ambiguities exert major constraints on the equations of condition. In these cases errors can be detected, e.g., those arising from the use of broad-cast ephemerides. When several integer numbers are found in the confidence intervals the values of the correlates suggest values matching the normal equation system. Considerable interdependencies of the equations of condition are evident. Consequently there is an increase in the values that are linked to an incorrect condition via satellite and station. Therefore the correlations between the Lagrange factors should be investigated more closely. It is useful to determine the ambiguities of a data set by observation times of different lengths. By comparing the double difference ambiguities calculated from these solutions an additional examination of the results is made possible. Particularly when base lines of more than 1000 km are used it turns out that with data resulting from shorter observation times integer numbers can be calculated that would either not result at all or only inaccurately from longer measurements. The use of correlates as indicators for incorrect conditions is not only suitable for evaluating ambiguities in GPS analysis. Moreover, all parameters that can be formulated in appropriate conditions may be examined in any case of problems regarding the analysis of data.Numéro de notice : 13191 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54906 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13191-02 30.61 Livre Centre de documentation Géodésie Disponible 13191-01 30.61 Livre Centre de documentation Géodésie Disponible The effect of broadleaf canopies on survey-grade horizontal GPS-GLONASS measurements / Thomas H. Meyer in Surveying and land information systems, vol 62 n° 4 (01/12/2002)
[article]
Titre : The effect of broadleaf canopies on survey-grade horizontal GPS-GLONASS measurements Type de document : Article/Communication Auteurs : Thomas H. Meyer, Auteur ; J.E. Bean, Auteur ; C.R. Ferguson, Auteur ; J.M. Naismith, Auteur Année de publication : 2002 Article en page(s) : pp 215 - 224 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] diffusion du rayonnement
[Termes IGN] feuille (végétation)
[Termes IGN] instrumentation Trimble
[Termes IGN] ligne de base
[Termes IGN] positionnement par GLONASS
[Termes IGN] positionnement par GPS
[Termes IGN] récepteur GPS
[Termes IGN] récepteur mixte
[Termes IGN] seuillage
[Termes IGN] signal GLONASS
[Termes IGN] signal GPSRésumé : (Auteur) A study was conducted to empirically determine the degradation of survey-grade GPS horizontal position measurements due to the effects of broadleaf forest canopies. The measurements were taken using GPS/GLONASS-capable receivers measuring C/A and P-codes, and carrier phase. Fourteen survey markers were chosen in central Connecticut to serve as reference makers for study. These markers had varying degrees of sky obstruction due to overhanging tree canopies. Sky obstruction was measured by photographing the sky with a 35 mm reflex camera fitted with a hemispherical lens. The negative was scanned and the image mapped using an equal-area projection to remove the distortion caused by the lens. The resulting digital image was thresholded to produce a black-and-white image in which a count of the black pixels is a measure of sky-area obstruction. The locations of the markers were determined independently before the study. During the study, each marker was occupied for four 20-minutes sessions over the period of one week in mid-july 1999. The locations of the study markers produced relatively long baselines, as compared with similar studies. We compared the accuracy of GPS-only vs. GPS&GLONASS as a function of sky obstruction. Based on our results, GLONASS observations did not improve of degrade the accuracy of the position measurements. There is a loss of 2 mm of accuracy per percent of sky obstruction for both GPS only and GPS&GLONASS. Numéro de notice : A2002-360 Affiliation des auteurs : non IGN Thématique : FORET/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22271
in Surveying and land information systems > vol 62 n° 4 (01/12/2002) . - pp 215 - 224[article]Radiofrequency interference and GPS: a growing concern / F. Butsch in GPS world, vol 13 n° 10 (October 2002)
[article]
Titre : Radiofrequency interference and GPS: a growing concern Type de document : Article/Communication Auteurs : F. Butsch, Auteur Année de publication : 2002 Article en page(s) : pp 40 - 50 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] brouillage
[Termes IGN] bruit (théorie du signal)
[Termes IGN] correction du signal
[Termes IGN] interférence
[Termes IGN] signal GPS
[Termes IGN] traitement du signalRésumé : (Editeur) Over the past couple of years, there has been extensive discussion of the potential interference that ultra-wideband (UWB) radio signals might cause to GPS once UWB devices proliferate across the planet. But GPS is also susceptible to interference from more conventional transmissions both accidental and intentional (jamming). For example, a particular directional television receiving antenna widely available in the consumer market contains an amplifier which can emit spurious radiation in the GPS L1 frequency band with sufficient power to interfere with GPS reception at distances of 200 meters or more. Harmonic emissions from high-power television transmitters might also be a threat to GPS. Furthermore, the GPS L2 frequency is susceptible to interference from out-of-band signals from transmitters operating in the lower part of the 1240 to 1300 MHz band which is shared by terrestrial radiolocation services and amateur radio operators. As for intentional interference, the weak GPS signals can be readily jammed either by hostile forces during conflicts or by hackers who could easily construct a GPS jammer from a surplus home-satellite television receiver. How susceptible are GPS signals to interference and how can such interference be monitored ? Numéro de notice : A2002-394 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26418
in GPS world > vol 13 n° 10 (October 2002) . - pp 40 - 50[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-02101 RAB Revue Centre de documentation En réserve L003 Disponible Future GPS and Galileo signal / K. de Jong in Geoinformatics, vol 5 n° 6 (01/09/2002)
[article]
Titre : Future GPS and Galileo signal Type de document : Article/Communication Auteurs : K. de Jong, Auteur Année de publication : 2002 Article en page(s) : pp 6 - 7 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales
[Termes IGN] fiabilité des données
[Termes IGN] Galileo
[Termes IGN] Global Positioning System
[Termes IGN] précision de localisation
[Termes IGN] signal Galileo
[Termes IGN] signal GPSRésumé : (Auteur) In the june 1999 issue of Geoinformatics, the benefits of Global Positioning System (GPS) signal modernization to the civil GPS community were discussed. With the decision of the European Union (EU) in march this year to develop its own satellite navigation system, Galileo, and have this system operational by 2008, this may be a good opportunity to look again at the modernized GPS and Galileo signals. Numéro de notice : A2002-263 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22174
in Geoinformatics > vol 5 n° 6 (01/09/2002) . - pp 6 - 7[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 262-02061 SL Revue Centre de documentation Revues en salle Disponible Improvement of GPS phase ambiguity resolution using prior height information as a quasi-observation / Jianjun Zhu in Geomatica, vol 56 n° 3 (September 2002)
[article]
Titre : Improvement of GPS phase ambiguity resolution using prior height information as a quasi-observation Type de document : Article/Communication Auteurs : Jianjun Zhu, Auteur ; Rock Santerre, Auteur Année de publication : 2002 Article en page(s) : pp 211 - 221 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bathymétrie
[Termes IGN] altitude
[Termes IGN] données GPS
[Termes IGN] GPS en mode cinématique
[Termes IGN] hauteur (coordonnée)
[Termes IGN] phase GPS
[Termes IGN] récepteur GPS
[Termes IGN] résolution d'ambiguïté
[Termes IGN] Saint-Laurent (fleuve)Résumé : (Auteur) La résolution des ambiguïtés sur les phases du GPS sur L1 est toujours difficile pour l'arpentage cinématique, particulièrement lorsque la ligne de base est longue. Une approche intéressante consiste à combiner les observations GPS à l'information d'autres systèmes d'arpentage ou d'autres sources pour améliorer la résolution des ambiguïtés. En levés bathymétriques, l'information antérieure sur la hauteur peut être obtenue à partir de marégraphes. La présente recherche est entreprise pour étudier comment utiliser l'information antérieure sur la hauteur et comment obtenir une solution stable. Il s'agit d'une méthode qui utilise la hauteur antérieure comme une quasi-observation. Celle-ci est ensuite utilisée dans la compensation avec les observations GPS. Dans cette contribution, un algorithme est d'abord développé pour le calcul de compensation avec la quasi-observation. La capacité de la quasi-observation d'améliorer la technique de recherche est ensuite étudiée en détail. Les résultats montrent que non seulement la quasi-observation peut renforcer les tests pour éliminer les solutions incorrectes, mais elle peut aussi changer avantageusement la structure de l'espace de recherche des ambiguïtés. La stabilité de la méthode est également examinée. Enfin, des tests sur place sont entrepris pour démontrer que l'approche proposée est efficace. Les résultats des tests montrent que pour les levés bathymétriques dans le fleuve Saint-Laurent, si la technique d'interpolation de la marée est utilisée et si l'assise, le tangage et le tirant d'eau du bateau sont considérés, une précision de la hauteur antérieure de 10 ou 20 centimètres peut être sélectionnée. Numéro de notice : A2002-256 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.5623/geomat-2002-0031 En ligne : https://cdnsciencepub.com/doi/abs/10.5623/geomat-2002-0031 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22167
in Geomatica > vol 56 n° 3 (September 2002) . - pp 211 - 221[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 035-02031 RAB Revue Centre de documentation En réserve L003 Disponible GPS signal multipath: a software simulator / S.H. Byun in GPS world, vol 13 n° 7 (July 2002)PermalinkVariation in point positioning accuracies for single frequency GPS users during solar maximum / S. Skone in Geomatica, vol 56 n° 2 (June 2002)PermalinkApplication des méthodes de résolution d'ambigüités sur la mesure de phase GPS à l'approche de précision / J.P. Chauveau (2002)PermalinkFast precise GPS positioning in the presence of ionospheric delays / Dennis Odijk (2002)PermalinkOn the accuracy of kinematic carrier phase GPS for airborne mapping / A.M. Bruton in Geomatica, vol 55 n° 4 (December 2001)PermalinkEvaluation d'un système de positionnement d'un véhicule sur route basé sur la fusion de données / E. Helou Helo (2001)PermalinkPermalinkDeutsche Beiträge zu GPS-Kampagnen des Scientific Committee on Antarctic Research (SCAR) 1995-1998 / R. Dietrich (2000)PermalinkPräzise Positionierung in regionalen GPS-Referenzstationsnetzen / Lambert Wanninger (2000)PermalinkUntersuchung von GPS-Beobachtungen für kleinräumige geodätische Netze / R. Hollmann (2000)Permalink