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Evaluation of strategies for the ultra-rapid orbit prediction of BDS GEO satellites / Wenxi Zhao in Geo-spatial Information Science, vol 26 n° 1 (March 2023)  

Public [article]  inGeo-spatial Information Science > vol 26 n° 1 (March 2023) . - pp 16 - 30 Titre : Evaluation of strategies for the ultra-rapid orbit prediction of BDS GEO satellites Type de document : Article/Communication Auteurs : Wenxi Zhao, Auteur ; Xiaolei Dai, Auteur ; Yidong Lou, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : pp 16 - 30 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] constellation BeiDou [Termes IGN] éclipse solaire [Termes IGN] orbite géostationnaire [Termes IGN] orbitographie [Termes IGN] rayonnement solaire Résumé : (auteur) The quality of BeiDou Navigation Satellite System (BDS) Geostationary Earth Orbit (GEO) ultra-rapid products is unsatisfactory because GEO satellites are nearly stationary relative to ground stations. To optimize the quality of these ultra-rapid orbit products, we investigated the effects of the fitting arc length, an a priori Solar-Radiation Pressure (SRP) model, and the along-track empirical acceleration on the prediction of BDS GEO satellite orbits. The predicted orbit arcs of 24-h were evaluated through comparisons with the corresponding observed orbit arc and Satellite Laser Ranging (SLR) observations. In both eclipse and non-eclipse seasons, accuracy of the orbit predictions obtained using a 48-h fitting arc length were better than those obtained using 24-h and 72-h fitting arc lengths. Although the overlapping precision of predicted orbits exhibited no obvious improvement when an a priori SRP model was employed, the systematic bias in the SLR residuals was significantly reduced. Specifically, the mean value of SLR residuals decreased from −0.248 m to −0.024 m during non-eclipse seasons and from −0.333 m to −0.041 m during eclipse seasons, respectively. In addition, when an empirical acceleration in the along-track direction was introduced, the three-Dimensional Root-Mean-Square (3D RMS) of overlapping orbits during eclipse seasons decreased from 2.964 to 1.080 m, which is comparable to that during non-eclipse seasons. Furthermore, the Standard Deviation (STD) of SLR residuals decreased from 0.419 to 0.221 m during eclipse seasons. The analysis of SRP estimates shows that the stability of SRP parameters was significantly enhanced after the introduction of along-track empirical acceleration in eclipse seasons. The optimal BDS GEO ultra-rapid orbit prediction products were yielded by using a 48-h fitting arc length, an a priori SRP model and an along-track empirical acceleration. Numéro de notice : A2023-182 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/10095020.2022.2071177 En ligne : https://doi.org/10.1080/10095020.2022.2071177 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102968 [article]

GNSS best integer equivariant estimation combining with integer least squares estimation: an integrated ambiguity resolution method with optimal integer aperture test / Liye Ma in GPS solutions, vol 26 n° 4 (October 2022)  

Public [article]  inGPS solutions > vol 26 n° 4 (October 2022) . - n° 100 Titre : GNSS best integer equivariant estimation combining with integer least squares estimation: an integrated ambiguity resolution method with optimal integer aperture test Type de document : Article/Communication Auteurs : Liye Ma, Auteur ; Yidong Lou, Auteur ; Liguo Lu, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 100 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] méthode des moindres carrés [Termes IGN] phase GNSS [Termes IGN] positionnement par GNSS [Termes IGN] précision du positionnement [Termes IGN] résolution d'ambiguïté Résumé : (auteur) Accurate and reliable carrier phase ambiguity resolution (AR) is the key to global navigation satellite system (GNSS) high-precision navigation and positioning applications. The integer least squares (ILS) estimation and the best integer equivariant (BIE) estimation are two widely used AR method, with the former considered to have the highest success rate and the latter to be optimal in the minimum mean squared error (MSE) sense. We analyzed three key issues of applying the BIE method in detail, including the use boundary of BIE, the number of candidates to be involved, and the weight determination among ambiguity candidates. It has been demonstrated that the BIE estimator is superior to ILS estimator from an overall perspective, but not always the best in each specific epoch. Therefore, we recommend constructing an integrated ambiguity resolution scheme that combines BIE with ILS, and we propose to adopt the optimal integer aperture (OIA) test as a criterion to distinguish the two. Moreover, a new criterion referred to the OIA test is proposed to determine the number of candidates involved in the BIE estimator. We also attempt to add the quadratic forms of baseline residuals into the weight function of BIE, aiming to reach a more accurate estimator. Finally, an integrated AR method that combines ILS with BIE and distinguished by the OIA test is proposed, named OIA-BIE. A set of real-measured vehicle data are tested to evaluate its performance, compared to least squares (LS), ILS, and the original BIE. The results show that the positioning accuracy of OIA-BIE is a little better than BIE, better than ILS, and significantly better than LS. Moreover, the average time consumption of ILS, BIE, and OIA-BIE are also evaluated, with 1.15, 14.62, and 3.71 ms, respectively, and OIA-BIE is four times more efficient than BIE. Numéro de notice : A2022-542 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01285-5 Date de publication en ligne : 03/07/2022 En ligne : https://doi.org/10.1007/s10291-022-01285-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101107 [article]

ON GLONASS pseudo-range inter-frequency bias solution with ionospheric delay modeling and the undifferenced uncombined PPP / Zheng Zhang in Journal of geodesy, vol 95 n° 3 (March 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 3 (March 2021) . - n°32 Titre : ON GLONASS pseudo-range inter-frequency bias solution with ionospheric delay modeling and the undifferenced uncombined PPP Type de document : Article/Communication Auteurs : Zheng Zhang, Auteur ; Yidong Lou, Auteur ; Zheng Fu, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n°32 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données GLONASS [Termes IGN] données GNSS [Termes IGN] erreur systématique de code différentiel [Termes IGN] erreur systématique interfréquence d'horloge [Termes IGN] harmonique sphérique [Termes IGN] modèle ionosphérique [Termes IGN] polarisation [Termes IGN] positionnement différentiel [Termes IGN] positionnement ponctuel précis [Termes IGN] retard ionosphèrique [Termes IGN] signal GLONASS Résumé : (auteur) With the development of multi-GNSS, the differential code bias (DCB) has been an increasing interest in the multi-frequency multi-GNSS community. Unlike code division multiple access (CDMA) mode used by GPS, BDS and Galileo etc., the GLONASS signals are modulated with frequency division multiple access (FDMA) mode. Up to now, the FDMA-aware GLONASS bias products are provided by two individual IGS analysis center (AC), i.e., CODE and GFZ. However, only the ionosphere-free (IF) combination IFB of P1 and P2 is available, while it is founded that the GLONASS IFB of GFZ on both frequencies are identical for the same receiver-satellite pair. In this contribution, the GLONASS IFB (inter-frequency bias) solution based on the spherical-harmonic (SH) ionospheric delay modeling as well as the undifferenced and uncombined PPP were carried out and evaluated. Based on the theoretical analysis, observations from 236 CMONOC stations and 172 IGS stations were collected for 2014 March and 2017 March for the numerical verification. The results suggested that the precision of IFB estimates was mainly subjected to the ionospheric status. Concerning the SH ionospheric delay modeling solution, the STD was 0.85 ns and 0.51 ns for 2014 and 2017, respectively. Concerning the undifferenced and uncombined PPP solution, the IFB was further dependent on the signal frequencies, and the STD was 1.43 ns and 1.94 ns for IFB1 and IFB2 in 2014, and the STD was 0.97 ns and 1.17 ns for IFB1 and IFB2 in 2017. When converted to the GF IFB from the individual IFB on each frequency, and compared to that of GF IFB of SH solution, it is revealed that the undifferenced and uncombined PPP solution has its advantages for IFB estimation on each individual frequency, and more efficient in data processing, while the solution based on the SH ionospheric delay modeling has its advantage in the precision of the GF IFB estimates. Thus, it is suggested that the SH model should be preferred for non-time-critical GF IFB concerned-only applications. Otherwise, the undifferenced and uncombined PPP solution is preferred. These IFB on each frequency was further converted to the ionosphere-free IFB and compared with the products of CODE analysis center. Numéro de notice : A2021-221 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01480-1 Date de publication en ligne : 22/02/2021 En ligne : https://doi.org/10.1007/s00190-021-01480-1 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97190 [article]

Research on empirical correction models of GPS Block IIF and BDS satellite inter-frequency clock bias / Xiaopeng Gong in Journal of geodesy, Vol 94 n°3 (March 2020)  

Public [article]  inJournal of geodesy > Vol 94 n°3 (March 2020) Titre : Research on empirical correction models of GPS Block IIF and BDS satellite inter-frequency clock bias Type de document : Article/Communication Auteurs : Xiaopeng Gong, Auteur ; Shengfeng Gu, Auteur ; Yidong Lou, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse harmonique [Termes IGN] décalage d'horloge [Termes IGN] données BeiDou [Termes IGN] données GPS [Termes IGN] erreur systématique interfréquence d'horloge [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Termes IGN] triple différence Résumé : (auteur) Triple-frequency observations will introduce an inter-frequency clock bias (IFCB) between the new frequency and the original dual-frequency observations. It has been verified that satellite IFCB can reach dozens of centimeters and several centimeters for GPS Block IIF satellite and BDS satellite, respectively. The existence of satellite IFCB will significantly affect undifferenced triple-frequency data processing. Based on 4-year data collected from 80 globally distributed stations, the long-term characteristics of IFCB coefficients obtained by using harmonic analysis have been studied. The results demonstrate that the coefficients of IFCB periodic model cannot be well fitted only by using sun elevation angle. Also, coefficients have obvious periodic characteristics and their periods differ among different satellites. Thus, a new linear-plus-periodic model is proposed to fit the long-term coefficients. Then, IFCB empirical correction models for 12 GPS Block IIF satellites and BDS GEO and IGSO satellites are built. In order to validate the correction model, IFCB standard deviation (STD), triple-frequency precise point positioning (PPP) and undifferenced extra-wide-lane (EWL) ambiguity resolution are employed. The results based on more than 4-year observations show that, with correction model applied, the average IFCB STD decreases by about 65.5% and 45.5% for GPS and BDS satellites, respectively. Compared to triple-frequency PPP without IFCB correction, triple-frequency PPP results with IFCB correction show that Up, North and East components accuracy are improved by 12.3%, 16.0% and 13.2%, respectively. Besides, IFCB correction will greatly improve the consistence of EWL fractional cycle bias among different stations and improve the success rate of EWL ambiguity resolution. Numéro de notice : A2020-157 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01365-9 Date de publication en ligne : 06/03/2020 En ligne : https://doi.org/10.1007/s00190-020-01365-9 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94808 [article]

Real-time clock prediction of multi-GNSS satellites and its application in precise point positioning / Yaquan Peng in Advances in space research, vol 64 n°7 (1 October 2019)  

Public [article]  inAdvances in space research > vol 64 n°7 (1 October 2019) . - pp 1445 - 1454 Titre : Real-time clock prediction of multi-GNSS satellites and its application in precise point positioning Type de document : Article/Communication Auteurs : Yaquan Peng, Auteur ; Yidong Lou, Auteur ; Xiaopeng Gong, Auteur ; YinTong Wang, Auteur ; Xiaolei Dai, Auteur Année de publication : 2019 Article en page(s) : pp 1445 - 1454 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] horloge atomique [Termes IGN] horloge du satellite [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement par Galileo [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] prédiction [Termes IGN] temps réel Résumé : (auteur) With the development of Global Navigation Satellite System (GNSS), multi-GNSS is expected to greatly benefit precise point positioning (PPP), especially during the outage of real time service (RTS). In this paper, we focus on the performance of multi-GNSS satellite clock prediction and its application in real-time PPP. Based on the statistical analysis of multi-system satellite clock products, a model consisting of polynomial and periodic terms is employed for multi-system satellite clock prediction. To evaluate the method proposed, both post-processed and real-time satellite clock products are employed in simulated real-time processing mode. The results show that the accuracy of satellite clock prediction is related to atomic clock type and satellite type. For GPS satellites, the average standard deviations (STDs) of Cs atomic clocks will reach as high as 0.65 ns while the STD of Rb atomic clocks is only about 0.15 ns. As for BDS and Galileo, the average STD of 2-hour satellite clock prediction are 0.30 ns and 0.06 ns, respectively. In addition, it is validated that real-time PPP can still achieve positioning accuracy of one to three decimeters by using products of 2-hour satellite clock prediction. Moreover, compared to the results of GPS-only PPP, multi-system can greatly enhance the accuracy of real-time PPP from 12.5% to 18.5% in different situations. Numéro de notice : A2019-410 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2019.06.040 Date de publication en ligne : 08/07/2019 En ligne : https://doi.org/10.1016/j.asr.2019.06.040 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93525 [article]

Evaluation of three ionospheric delay computation methods for ground-based GNSS receivers / Liang Chen in GPS solutions, vol 22 n° 4 (October 2018)  

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Modeling tropospheric wet delays with national GNSS reference network in China for BeiDou precise point positioning / Fu Zheng in Journal of geodesy, vol 92 n° 5 (May 2018)  

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Benefits of satellite clock modeling in BDS and Galileo orbit determination / Yun Qing 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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BeiDou phase bias estimation and its application in precise point positioning with triple-frequency observable / Shengfeng Gu in Journal of geodesy, vol 89 n° 10 (october 2015)  

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Estimating the yaw-attitude of an BDS IGSO and MEO satellites / Xiaolei Dai in Journal of geodesy, vol 89 n° 10 (october 2015)  

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Ionospheric effects in uncalibrated phase delay estimation and ambiguity-fixed PPP based on raw observable model / Shengfeng Gu in Journal of geodesy, vol 89 n° 5 (May 2015)  

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