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Real-time cycle-slip detection and repair for BeiDou triple-frequency undifferenced observations / Y.-F. Yao in Survey review, vol 48 n° 350 (September 2016)  

Public [article]  inSurvey review > vol 48 n° 350 (September 2016) . - pp 367 - 375 Titre : Real-time cycle-slip detection and repair for BeiDou triple-frequency undifferenced observations Type de document : Article/Communication Auteurs : Y.-F. Yao, Auteur ; J.-X. Gao, Auteur ; J. Wang, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 367 - 375 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] détection d'anomalie [Termes IGN] glissement de cycle [Termes IGN] phase [Termes IGN] positionnement par BeiDou [Termes IGN] récepteur trifréquence [Termes IGN] signal BeiDou [Termes IGN] temps réel Résumé : (auteur) A new method of real-time cycle-slip detection and repair for BeiDou navigation satellite system (BDS) triple-frequency undifferenced observations is proposed. The method, which is based on code–phase and geometry-free phase combinations, composes linearly independent combination observations to uniquely determine the cycle-slip of original frequency phase observations in two independent steps. First, two extra-wide lane (EWL) code–phase combinations are utilised to determine the EWL combination cycle-slips. The sum of the carrier phase combination coefficients is zero. Second, the geometry-free phase combination with a non-zero sum of combination coefficients composes linearly independent combination observations with two code–phase combinations. Ionospheric delay variance systematic deviation is corrected with several previous carrier-phase observations without cycle-slip, which seriously affect the accuracy of the geometry-free phase combination observations. The BDS triple-frequency carrier-phase and code observations of different satellite types at 30 s sampling interval, which involve increased active ionospheric conditions in 1 day, are utilised to test the method. Results show that the proposed method can efficiently detect and accurately repair any cycle-slip combinations in real-time for different satellite types under active ionospheric conditions. No erroneous and leakage judgments are observed in the test. Numéro de notice : A2016-642 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2015.1133518 En ligne : https://doi.org/10.1080/00396265.2015.1133518 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81847 [article]

External error modelling with combined model in terrestrial laser scanning / J. Wang in Survey review, vol 48 n° 346 (January 2016)  

Public [article]  inSurvey review > vol 48 n° 346 (January 2016) . - pp 40 - 50 Titre : External error modelling with combined model in terrestrial laser scanning Type de document : Article/Communication Auteurs : J. Wang, Auteur ; H. Kutterer, Auteur ; X. Fang, Auteur Année de publication : 2016 Article en page(s) : pp 40 - 50 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] étalonnage de capteur (imagerie) [Termes IGN] itération [Termes IGN] modèle de Gauss-Helmert [Termes IGN] réfraction atmosphérique [Termes IGN] télémétrie laser sur satellite [Termes IGN] télémétrie laser terrestre Résumé : (auteur) Terrestrial laser scanning (TLS) is a promising tool in geodetic applications. Data quality of outdoor TLS measurements is considerably limited by external errors caused by atmospheric variations and object related factors. In this study, external models related to atmospheric refraction, beam wander and incidence angle were introduced and integrated into a seven-parameter similarity transformation (7PST) model to compose a combined model. The combined model was rigorously adjusted by an iterative Gauss–Helmert (GH) model primarily to estimate external calibration parameters and transformation parameters simultaneously. In the application on a dam surface, a t-test showed that a significant external calibration parameter was the range scale, which mainly corresponded with the incidence angle model. The precision of estimated representative points was improved by approximately 50% with the proposed method. The presented models show a great potential for detecting external errors and registering multiple scans in outdoor applications. Numéro de notice : A2016-045 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/00396265.2015.1097589 En ligne : https://doi.org/10.1080/00396265.2015.1097589 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79638 [article]

Reliability of partial ambiguity fixing with multiple GNSS constellations / J. Wang in Journal of geodesy, vol 87 n° 1 (January 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 1 (January 2013) . - pp 1 - 14 Titre : Reliability of partial ambiguity fixing with multiple GNSS constellations Type de document : Article/Communication Auteurs : J. Wang, Auteur ; Y. Feng, Auteur Année de publication : 2013 Article en page(s) : pp 1 - 14 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] matrice [Termes IGN] positionnement cinématique en temps réel [Termes IGN] résolution d'ambiguïté [Termes IGN] traitement de données GNSS Résumé : (Auteur) Reliable ambiguity resolution (AR) is essential to real-time kinematic (RTK) positioning and its applications, since incorrect ambiguity fixing can lead to largely biased positioning solutions. A partial ambiguity fixing technique is developed to improve the reliability of AR, involving partial ambiguity decorrelation (PAD) and partial ambiguity resolution (PAR). Decorrelation transformation could substantially amplify the biases in the phase measurements. The purpose of PAD is to find the optimum trade-off between decorrelation and worst-case bias amplification. The concept of PAR refers to the case where only a subset of the ambiguities can be fixed correctly to their integers in the integer least squares (ILS) estimation system at high success rates. As a result, RTK solutions can be derived from these integer-fixed phase measurements. This is meaningful provided that the number of reliably resolved phase measurements is sufficiently large for least-square estimation of RTK solutions as well. Considering the GPS constellation alone, partially fixed measurements are often insufficient for positioning. The AR reliability is usually characterised by the AR success rate. In this contribution, an AR validation decision matrix is firstly introduced to understand the impact of success rate. Moreover the AR risk probability is included into a more complete evaluation of the AR reliability. We use 16 ambiguity variance–covariance matrices with different levels of success rate to analyse the relation between success rate and AR risk probability. Next, the paper examines during the PAD process, how a bias in one measurement is propagated and amplified onto many others, leading to more than one wrong integer and to affect the success probability. Furthermore, the paper proposes a partial ambiguity fixing procedure with a predefined success rate criterion and ratio test in the ambiguity validation process. In this paper, the Galileo constellation data is tested with simulated observations. Numerical results from our experiment clearly demonstrate that only when the computed success rate is very high, the AR validation can provide decisions about the correctness of AR which are close to real world, with both low AR risk and false alarm probabilities. The results also indicate that the PAR procedure can automatically chose adequate number of ambiguities to fix at given high-success rate from the multiple constellations instead of fixing all the ambiguities. This is a benefit that multiple GNSS constellations can offer. Numéro de notice : A2013-069 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0573-4 Date de publication en ligne : 12/06/2012 En ligne : https://doi.org/10.1007/s00190-012-0573-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32207 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2013011	SL	Revue	Centre de documentation	Revues en salle	Disponible

On the detection of systematic errors in terrestrial laser scanning data / J. Wang in Journal of applied geodesy, vol 6 n° 3-4 (November 2012)  

Public [article]  inJournal of applied geodesy > vol 6 n° 3-4 (November 2012) . - pp 187 - 192 Titre : On the detection of systematic errors in terrestrial laser scanning data Type de document : Article/Communication Auteurs : J. Wang, Auteur ; H. Kutterer, Auteur ; X. Fang, Auteur Année de publication : 2012 Article en page(s) : pp 187 - 192 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] algorithme ICP [Termes IGN] barrage [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] erreur systématique [Termes IGN] lasergrammétrie [Termes IGN] modèle de Gauss-Helmert [Termes IGN] segmentation d'image [Termes IGN] télémétrie laser sur satellite Résumé : (Auteur) Quality descriptions are parts of the key tasks of geodetic data processing. Systematic errors should be detected and avoided in order to insure the high quality standards required by structural monitoring. In this study, the iterative closest point (ICP) method was invested to detect systematic errors in two overlapping data sets. There are three steps to process the systematic errors: firstly, one of the data sets was transformed to a reference system by the introduction of the Gauss–Helmert (GH) model. Secondly, quadratic form estimation and segmentation methods are proposed to guarantee the overlapping data sets. Thirdly, the ICP method was employed for a finer registration and detecting the systematic errors. A case study was casted in which a dam surface in Germany was scanned by terrestrial laser scanning (TLS) technology. The results indicated that with the conjugation of ICP algorithm the accuracy of the data sets was improved approximately by 1.6 mm. Numéro de notice : A2012-598 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1515/jag-2012-0025 En ligne : http://www.degruyter.com/view/j/jag.2012.6.issue-3-4/jag-2012-0025/jag-2012-0025 [...] Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32044 [article]

Safety at the wheel: improving KGPS/INS performance and reliability / J. Wang in GPS world, vol 14 n° 5 (May 2003)

Public [article]  inGPS world > vol 14 n° 5 (May 2003) . - pp 16 - 26 Titre : Safety at the wheel: improving KGPS/INS performance and reliability Type de document : Article/Communication Auteurs : J. Wang, Auteur ; C. Wilson, Auteur Année de publication : 2003 Article en page(s) : pp 16 - 26 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] GPS en mode cinématique [Termes IGN] GPS-INS [Termes IGN] précision décimétrique [Termes IGN] véhicule automobile Résumé : (Editeur) Oncoming automobile capabilities such as lane-departure warnings and collision avoidance require real-time positioning accuracy of 10 centimeters or less. A new system integrating kinematic GPS, inertial measurement, wheel-speed data, and a digital map shows promise for this life-saving feature. Numéro de notice : A2003-420 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26500 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
067-03051	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Stochastic assessment of GPS carrier phase measurements for precise static relative positioning / J. Wang in Journal of geodesy, vol 76 n° 2 (February 2002)  

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