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Partial GNSS ambiguity resolution in coordinate domain / Shengyue Ji in Survey review, vol 51 n° 369 (November 2019)  

Public [article]  inSurvey review > vol 51 n° 369 (November 2019) . - pp 525 - 532 Titre : Partial GNSS ambiguity resolution in coordinate domain Type de document : Article/Communication Auteurs : Shengyue Ji, Auteur ; Rongyao Du, Auteur ; Wu Chen, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 525 - 532 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] coordonnées GNSS [Termes descripteurs IGN] erreur de positionnement [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (auteur) Traditionally, if full ambiguity resolution is not successful, partial ambiguity resolution (PAR) will be tried. However, identifying which subset of ambiguities to fix is not easy and is still an open problem. Since the actual purpose of most applications is positioning, rather than fixing all or part of the ambiguities, in this research, we are trying to bypass the problem of identifying which subset of ambiguities to fix and provide a partial solution in the coordinate domain for the bias-free case. The basic idea is that with a user-defined failure rate, we can find a group of ambiguity candidates and each will provide one position. The partial solution is constructed based on these positions together with an indicator to show its maximum positioning error with user-defined reliability. In order to meet various user requirements, different kinds of partial solutions in coordinate domain are proposed. Different from the traditional PAR methods, the new method still works with all the ambiguities (i.e. the complete vector), but works with the different possible values that the complete ambiguity vector may take. The validness and applicability of the proposed partial solution are demonstrated-based practical BeiDou triple-frequency observations. Numerical results show that some partial solutions can be more accurate, while others can meet higher reliability or integrity requirement. Numéro de notice : A2019-574 Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2018.1490870 date de publication en ligne : 13/07/2018 En ligne : https://doi.org/10.1080/00396265.2018.1490870 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94454 [article]

Triple-frequency PPP ambiguity resolution with multi-constellation GNSS: BDS and Galileo / Xingxing Li in Journal of geodesy, vol 93 n° 8 (August 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 8 (August 2019) . - pp 1105 - 1122 Titre : Triple-frequency PPP ambiguity resolution with multi-constellation GNSS: BDS and Galileo Type de document : Article/Communication Auteurs : Xingxing Li, Auteur ; Xin Li, Auteur ; Gege Liu, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 1105 - 1122 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] constellation BeiDou [Termes descripteurs IGN] constellation GNSS [Termes descripteurs IGN] estimation de position [Termes descripteurs IGN] fréquence multiple [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] positionnement cinématique [Termes descripteurs IGN] positionnement par Galileo [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] positionnement statique [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (auteur) Multi-constellation GNSS (multi-GNSS) and multi-frequency signals open new prospects for fast ambiguity resolution (AR) of precise point positioning (PPP). Currently, all the BDS and Galileo satellites are capable of transmitting signals on three or more frequencies. In this contribution, we investigate the triple-frequency PPP ambiguity resolution with B1, B2 and B3 observations from BDS satellites and E1, E5a and E5b observations from Galileo satellites and evaluate the contribution of BDS + Galileo combination to triple-frequency PPP AR. The uncalibrated phase delay (UPD) products are estimated based on triple-frequency observations, and the temporal characteristic as well as the residual distributions are analyzed. Our results show that the extra-wide-lane (EWL) and wide-lane (WL) UPDs for BDS and Galileo satellites are both stable during the 30 days and the daily narrow-lane (NL) UPD series are also steady with no obvious fluctuation. The Galileo UPDs exhibit better performance than BDS UPDs due to the high-quality observations. It is also interesting to find that the EWL UPD corrections for all Galileo satellites are very close to the zero. With the precise UPD products, the triple-frequency PPP AR with BDS and Galileo observations was implemented in both static and kinematic modes. Compared to the ambiguity-float solution, the performance can be significantly improved by triple-frequency PPP AR with the positioning accuracy improved by 30–70% in both static and kinematic modes. Moreover, the triple-frequency PPP fixed solutions also present better performance than the dual-frequency PPP fixed solutions in terms of time to the first fix and positioning accuracy, especially for the Galileo-only and BDS + Galileo solutions. And the fusion of multi-GNSS (BDS and Galileo) can further improve the position estimations compared to the single system with more satellites and better spatial geometry. Numéro de notice : A2019-380 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01229-x date de publication en ligne : 01/02/2019 En ligne : https://doi.org/10.1007/s00190-019-01229-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93457 [article]

Multi-dimensional particle filter-based estimation of inter-system phase biases for multi-GNSS real-time integer ambiguity resolution / Yumiao Tian in Journal of geodesy, vol 93 n°7 (July 2019)  

Public [article]  inJournal of geodesy > vol 93 n°7 (July 2019) . - pp 1073 - 1087 Titre : Multi-dimensional particle filter-based estimation of inter-system phase biases for multi-GNSS real-time integer ambiguity resolution Type de document : Article/Communication Auteurs : Yumiao Tian, Auteur ; Zhizhao Liu, Auteur ; Frank Neitzel, Auteur Année de publication : 2019 Article en page(s) : pp 1073 - 1087 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] analyse multidimensionnelle [Termes descripteurs IGN] constellation GNSS [Termes descripteurs IGN] erreur systématique inter-systèmes [Termes descripteurs IGN] filtre [Termes descripteurs IGN] phase GNSS [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] précision du positionnement [Termes descripteurs IGN] résolution d'ambiguïté [Termes descripteurs IGN] temps réel [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) In multi-GNSS integration, fixing inter-system double-difference ambiguities to integers is still a challenge due to the existence of inter-system biases (ISB) when mixed types of GNSS receivers are used. It has been shown that when ISB is known, the inter-system ambiguities can be fixed and the reliability of ambiguity fixing can be improved significantly, especially under poor conditions when the number of observed satellites is small. In traditional methods, the intra-system ambiguity is fixed first; then, the ISB is estimated to ultimately fix the inter-system ambiguity. In our work, we use the particle filter-based method to estimate the ISB parameter and fix the inter-system ambiguities to integers at the same time. This method shows higher reliability and higher ambiguity fixing rate. Nevertheless, the existing particle filter approach for ISB parameter estimation is a one-dimensional algorithm. When satellites from three or more systems are observed, there are two or more ISB parameters. We extend the current one-dimensional particle filter approach to multi-dimensional case and estimate multi-ISB parameters in this study. We first present a multi-dimensional particle filter approach that can estimate multi-ISB parameters simultaneously. We also show that the RATIO values can be employed to judge the quality of multi-dimensional ISB values. Afterward, a two-dimensional particle filter approach is taken as an example to validate this approach. For example, in the experiment of GPS L5, Galileo E5a and QZSS L5 integration with 6 satellites using the IGS baseline SIN0-SIN1, only three ambiguities are resolved to integer when the ISBs are unknown. The integer ambiguity fixing rate is 41.0% with 53% of the ambiguity-fixed solutions having positioning errors larger than 3 cm. However, when our approach is adopted, the number of integer ambiguity parameters increases to five. The integer ambiguity fixing rate increases to 99.7% with 100% of ambiguity-fixed solutions having positioning errors smaller than 3 cm. Numéro de notice : A2019-359 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-01226-6 date de publication en ligne : 29/01/2019 En ligne : https://doi.org/10.1007/s00190-018-01226-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93427 [article]

The improvement in integer ambiguity resolution with INS aiding for kinematic precise point positioning / Xiaohong Zhang in Journal of geodesy, vol 93 n°7 (July 2019)  

Public [article]  inJournal of geodesy > vol 93 n°7 (July 2019) . - pp 993 - 1010 Titre : The improvement in integer ambiguity resolution with INS aiding for kinematic precise point positioning Type de document : Article/Communication Auteurs : Xiaohong Zhang, Auteur ; Feng Zhu, Auteur ; Yuxi Zhang, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 993 - 1010 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] affaiblissement de la précision [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] délai d'obtention de la première position [Termes descripteurs IGN] GNSS-INS [Termes descripteurs IGN] milieu urbain [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] précision du positionnement [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (auteur) Despite the benefits of integer ambiguity resolution (IAR) in precise point positioning (PPP), observation outages and harsh signal environments still impact float ambiguity estimation in kinematic surveying, consequently resulting in ambiguity-fixed failure. The inertial navigation system (INS) is an autonomous and spontaneous positioning one, which could provide continuous and superior positioning accuracy over short time. Thus, the INS attains more accurate position than code solution. Moreover, the tight integration of INS and PPP is capable of continuous operation where there are less than four satellites available. These advantages can improve float ambiguity estimation and assist in re-initializing the interrupted ambiguity and PPP solution. Based on the good quality of float ambiguity, the ambiguity dilution precision (ADOP) and the size of integer ambiguity search space are reduced, and then, the IAR-PPP is improved. In this work, the INS aiding effect on IAR-PPP was revealed by the sufficient theoretical analysis and performance assessment. A ring laser gyroscope-based navigation-grade IMU and a fiber optic gyroscope-based tactical-grade IMU were utilized to conduct experiments in an open-sky environment and urban area. The assessment adopted the following aspects of ADOP, bootstrapping success rate, time to fix and position errors. It is found that IAR-PPP with INS aiding achieves an enhanced performance during GPS outage when INS could deliver a superior accurate position. For the navigation- and tactical-grade IMU, the INS-aided ambiguity re-fixing performance can be classified as three levels: significant improvement for the outage duration less than 10 s, moderate improvement for the outage duration from 10 to 60 s and a little or zero improvement for the outage duration longer than 60 s. From the viewpoint of the INS-predicted position domain, an accuracy better than 0.1 m and 1.0 m is required for the significant and moderate improvement, while one can only achieve a little or zero improvement if the position error is larger than 1.0 m. Besides, we also performed the INS-aided IAR-PPP in real urban environment. For the urban environments, the span of clean data is often shorter than 30 min due to intermittent signal interruptions; thus, ambiguity re-fixing for PPP always fails. INS-aided information could bridge the data gaps and achieve fast ambiguity re-fixing. In summary, INS aiding information is capable of improving IAR-PPP performance significantly over a short GPS outage. Numéro de notice : A2019-356 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1222-3 date de publication en ligne : 08/12/2018 En ligne : https://link.springer.com/article/10.1007/s00190-018-1222-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93424 [article]

On-the-fly ambiguity resolution involving only carrier phase measurements for stand-alone ground-based positioning systems / Tengfei Wang in GPS solutions, vol 23 n° 2 (April 2019)  

Public [article]  inGPS solutions > vol 23 n° 2 (April 2019) Titre : On-the-fly ambiguity resolution involving only carrier phase measurements for stand-alone ground-based positioning systems Type de document : Article/Communication Auteurs : Tengfei Wang, Auteur ; Zheng Yao, Auteur ; Mingquan Lu, Auteur Année de publication : 2019 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] ambiguïté entière [Termes descripteurs IGN] compensation Lambda [Termes descripteurs IGN] double différence [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] positionnement absolu [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] résolution d'ambiguïté [Termes descripteurs IGN] station permanente Résumé : (Auteur) Despite the wide use of the global navigation satellite system (GNSS), its performance can be severely degraded due to blockage and vulnerability to interference. Stand-alone ground-based positioning systems can provide positioning services in the absence of GNSS signals and have tremendous application potential. For precise point positioning in ground-based systems, ambiguity resolution (AR) is a key issue. On-the-fly (OTF) AR methods are desirable for reasons of convenience. The existing methods usually linearize a nonlinear problem approximately by a series expansion that is based on an initial position estimation obtained by code measurements or measuring instruments. However, if the initial position estimation contains relatively large errors, the convergence of existing methods cannot be ensured. We present a new OTF-AR method based on the double difference square (DDS) observation model for ground-based precise point positioning, which involves only carrier phase measurements. The initial solution obtained from the DDS model is sufficiently accurate to obtain a float solution by linearization, and this step only requires the frequency synchronization of base stations. Further, if the clock differences of the base stations are accurately calibrated, a fixed solution can be obtained by employing the LAMBDA algorithm. Numerical simulations and a real-world experiment are conducted to validate the proposed method. Both the simulations and the experimental results show that the proposed method can achieve high-accuracy positioning. These results enable precise point positioning to be applied in situations where no reliable code measurements or other measuring instruments are available for stand-alone ground-based positioning systems. Numéro de notice : A2019-058 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-019-0825-3 date de publication en ligne : 02/02/2019 En ligne : http://dx.doi.org/10.1007/s10291-019-0825-3 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92090 [article]

Estimating and assessing Galileo satellite fractional cycle bias for PPP ambiguity resolution / Guorui Xiao in GPS solutions, vol 23 n° 1 (January 2019)  

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Undifferenced zenith tropospheric modeling and its application in fast ambiguity recovery for long-range network RTK reference stations / Dezhong Chen in GPS solutions, vol 23 n° 1 (January 2019)  

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Differential positioning based on the orthogonal transformation algorithm with GNSS multi-system / Xiao Liang in GPS solutions, vol 22 n° 3 (July 2018)  

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A sequential network approach for estimating GPS satellite phase biases at the PPP-AR producer-side / Omid Kamali in GPS solutions, vol 22 n° 3 (July 2018)  

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Multi-GNSS phase delay estimation and PPP ambiguity resolution : GPS, BDS, GLONASS, Galileo / Xingxing Li in Journal of geodesy, vol 92 n° 6 (June 2018)  

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On the impact of GNSS ambiguity resolution: geometry, ionosphere, time and biases / Amir Khodabandeh in Journal of geodesy, vol 92 n° 6 (June 2018)  

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Amélioration des calculs GNSS à façon du SGN / Mathilde Kremp (2018) 

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L'analyse des performance RTK dans la zone urbaine / Mohamed Hamza Megrerouche in Bulletin des sciences géographiques, n° 31 (2017 - 2018)

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Performance analysis of BDS/GPS precise point positioning with undifferenced ambiguity resolution / Min Wang in Advances in space research, vol 60 n° 12 (15 December 2017)  

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Assessment of PPP integer ambiguity resolution using GPS, GLONASS and BeiDou (IGSO, MEO) constellations / Yanyan Liu in GPS solutions, vol 21 n° 4 (October 2017)  

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