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Improving undifferenced precise satellite clock estimation with BDS-3 quad-frequency B1I/B3I/B1C/B2a observations for precise point positioning / Guoqiang Jiao in GPS solutions, vol 27 n° 1 (January 2023)  

Public [article]  inGPS solutions > vol 27 n° 1 (January 2023) . - n° 28 Titre : Improving undifferenced precise satellite clock estimation with BDS-3 quad-frequency B1I/B3I/B1C/B2a observations for precise point positioning Type de document : Article/Communication Auteurs : Guoqiang Jiao, Auteur ; Shuli Song, Auteur ; Ke Su, Auteur Année de publication : 2023 Article en page(s) : n° 28 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] décalage d'horloge [Termes IGN] données BeiDou [Termes IGN] erreur systématique interfréquence d'horloge [Termes IGN] fréquence multiple [Termes IGN] horloge du satellite [Termes IGN] positionnement ponctuel précis Résumé : (auteur) Estimates of satellite clock offsets typically employ dual-frequency undifferenced (UD) ionospheric-free (IF) observations from global network. The third-generation BeiDou Navigation Satellite System (BDS-3) can transmit B1I (1561.098 MHz), B3I (1268.52 MHz), B1C (1575.42 MHz), B2a (1176.45 MHz), B2b (1207.14 MHz) and B2ab (1191.795 MHz) signals. To make full use of the advantage of BDS-3 multi-frequency signals and improve BDS-3 service performance, we present some new quad-frequency satellite clock estimation techniques using B1I/B3I/B1C/B2a signals, which are QFIF0 model combining B1I/B3I and B1C/B2a IF observables, QFIF1 model combining the B1I/B3I, B3I/B1C and B1I/B2a IF observables, QFIF2 model combining B1I/B3I and B1I/B3I/B1C/B2a IF observables, and quad-frequency uncombined QFUC model, respectively. These new techniques only improve the performance of satellite clock estimation by fully utilizing the BDS-3 multi-frequency observations on the premise of ensuring the dual-frequency IF datum but also obtain the corresponding inter-frequency clock bias (IFCB) simultaneously. The quad-frequency satellite clock offsets are evaluated in terms of the clock offset precision, the modified Allan deviation (MDEV) and precise point positioning (PPP) performances. The new methods can improve the performances of the estimated clock offsets compared with the traditional dual-frequency IF model. The precision for the estimated clock offsets using quad-frequency satellite clock estimation models can be improved by 13–26% in terms of standard deviation (STD). The improvement of frequency stability ranges from 0 to 24%, especially for the short-term stability, which can reach 12% and 24% for B1I/B3I and B1C/B2a clock offsets, respectively. Similarly, the corresponding PPP performance has also been better improved with respect to those of using traditional dual-frequency IF clock offsets. Thus, the proposed quad-frequency satellite clock estimation techniques can be well applied into precise satellite clock estimation. Numéro de notice : A2023-025 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01364-7 Date de publication en ligne : 29/11/2022 En ligne : https://doi.org/10.1007/s10291-022-01364-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102260 [article]

Multi-frequency simulation of ionospheric scintillation using a phase-screen model / Fernando D. Nunes in Navigation : journal of the Institute of navigation, vol 69 n° 4 (Fall 2022)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 69 n° 4 (Fall 2022) . - n° 545 Titre : Multi-frequency simulation of ionospheric scintillation using a phase-screen model Type de document : Article/Communication Auteurs : Fernando D. Nunes, Auteur ; Fernando M.G. Sousa, Auteur ; José M.V. Marçal, Auteur Année de publication : 2022 Article en page(s) : n° 545 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] amplitude [Termes IGN] correction ionosphérique [Termes IGN] fréquence multiple [Termes IGN] ionosphère [Termes IGN] méthode de Monte-Carlo [Termes IGN] phase [Termes IGN] scintillation [Termes IGN] série temporelle [Termes IGN] signal GNSS [Termes IGN] teneur totale en électrons Résumé : (auteur) A fast Monte Carlo technique to simulate equatorial ionospheric scintillation on global navigation satellite system signals is proposed. The algorithm uses a single-layer phase-screen model of the ionosphere and the scintillation is expressed as a Huygens-Fresnel integral (HFI). By assuming a specially-tailored random phase screen, the HFI can be expressed in closed form as a combination of Fresnel integrals. We statistically characterize the amplitude and phase computed by the HFI for different values of the scintillation index S4. Results for the L1, L2, and L5 bands were obtained and compared with real data, showing good agreement. Some of the advantages of the proposed technique are: (a) the amplitude and phase of the scintillation process are simultaneously obtained; (b) arbitrarily long ionospheric scintillation time series with pre-defined stationary characteristics are synthesized; and (c) several scintillation time series corresponding to different carrier frequencies are generated using a common phase-screen model. Numéro de notice : A2022-918 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.545 Date de publication en ligne : 18/06/2022 En ligne : https://doi.org/10.33012/navi.545 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102446 [article]

Toward BDS/Galileo/GPS/QZSS triple-frequency PPP instantaneous integer ambiguity resolutions without atmosphere corrections / Jun Tao in GPS solutions, vol 26 n° 4 (October 2022)  

Public [article]  inGPS solutions > vol 26 n° 4 (October 2022) . - n° 127 Titre : Toward BDS/Galileo/GPS/QZSS triple-frequency PPP instantaneous integer ambiguity resolutions without atmosphere corrections Type de document : Article/Communication Auteurs : Jun Tao, Auteur ; Guo Chen, Auteur ; Jing Guo, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 127 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] correction atmosphérique [Termes IGN] erreur de phase [Termes IGN] fréquence multiple [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement par Galileo [Termes IGN] positionnement par GPS [Termes IGN] positionnement ponctuel précis [Termes IGN] Quasi-Zenith Satellite System [Termes IGN] résolution d'ambiguïté [Termes IGN] temps de convergence Résumé : (auteur) Multi-frequency precise point positioning (PPP) has drawn attention along with the modernization of the Global Navigation Satellite Systems. There are now nearly 90 satellites providing multi-frequency signals. This contribution aims to achieve fast convergence of a few seconds for BDS/Galileo/GPS/QZSS integrated triple-frequency PPP with integer ambiguity resolution (IAR) without atmosphere corrections. A unified model of an uncombined and undifferenced manner for PPP-IAR with dual- and triple-frequency observations is presented. The uncalibrated phase delays (UPD) of extra wide-lane (EWL), wide-lane (WL), and N1 ambiguities for triple-frequency PPP are estimated with standard deviations of 0.02, 0.05, and 0.10 cycles achieved, respectively. The PPP-IAR validation based on 20 stations evenly distributed in China is conducted using UPD products generated from a regional network covering a large part of China. The EWL, WL, and N1 ambiguities are sequentially fixed utilizing the least-squares ambiguity decorrelation adjustment (LAMBDA) technique. In terms of convergence time, PPP instantaneous IAR is achievable without using atmosphere corrections, thanks to the contribution of the multi-frequency and multi-constellation observations. This has been proved by performing PPP-IAR restart every 10-min over 2520 times in our case study. For PPP-IAR solutions produced with BDS/Galileo/GPS/QZSS triple-frequency observations with an interval of 1 s, the convergence is fulfilled within 1 s for the horizontal components with an accuracy of better than 5 cm, while 2 s for the vertical component with better than 10 cm accuracy, and both are at 95% confidence level. Numéro de notice : A2022-714 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01287-3 Date de publication en ligne : 13/08/2022 En ligne : https://doi.org/10.1007/s10291-022-01287-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101595 [article]

Ambiguity resolution for smartphone GNSS precise positioning: effect factors and performance / Bofeng Li in Journal of geodesy, vol 96 n° 9 (September 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 9 (September 2022) . - n° 63 Titre : Ambiguity resolution for smartphone GNSS precise positioning: effect factors and performance Type de document : Article/Communication Auteurs : Bofeng Li, Auteur ; Weikai Miao, Auteur ; Guang'e Chen, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 63 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] ambiguïté entière [Termes IGN] fréquence multiple [Termes IGN] phase GNSS [Termes IGN] positionnement cinématique en temps réel [Termes IGN] précision du positionnement [Termes IGN] résolution d'ambiguïté [Termes IGN] signal GNSS [Termes IGN] téléphone intelligent Résumé : (auteur) With the availability of Global Navigation Satellite Systems raw measurements in smartphones, high-precision positioning using smartphones has become possible in recent years. Integer ambiguity resolution (IAR) is critical for smartphone precise positioning, which would be more difficult in smartphones and affected by various factors. In this paper, we will numerically study the effect factors for integer property of phase ambiguities, data quality, IAR efficiency and positioning accuracy for the smartphone. The results show that integer property of phase ambiguities and data quality are governed not only by the smartphone brands and embedded antennas, but also by the mobile operating system and smartphone attitudes. In general, the different constant offsets exist for the different frequency ambiguities, and the ambiguities are fixable once the corresponding offsets are calibrated. With the operating system of EMUI 9.0, the ambiguities are fixable for Xiaomi Mi8 but not for Huawei Mate20. However, with the updated operating system of EMUI 9.0.1, the ambiguities of Huawei Mate20 become fixable. Besides the smartphone brands and embedded antennas, the smartphone attitudes significantly affect the data quality, such as carrier-to-noise density ratio (C/N0) values, data availability and observation precisions, thus affecting the ambiguity fixing rate and positioning accuracy. The ambiguity fixing rates differ from attitudes by 17%, and generally, the upward attitude has the best performance. Finally, the kinematic positioning results indicate that only the meter-level accuracy is obtained with an embedded antenna, while the centimeter to decimeter-level accuracy is achievable with the external antenna. Numéro de notice : A2022-667 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01652-7 Date de publication en ligne : 05/09/2022 En ligne : https://doi.org/10.1007/s00190-022-01652-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101531 [article]

Multi-frequency phase-only PPP-RTK model applied to BeiDou data / Pengyu Hou in GPS solutions, vol 26 n° 3 (July 2022)  

Public [article]  inGPS solutions > vol 26 n° 3 (July 2022) . - n° 76 Titre : Multi-frequency phase-only PPP-RTK model applied to BeiDou data Type de document : Article/Communication Auteurs : Pengyu Hou, Auteur ; Baocheng Zhang, Auteur ; Yury V. Yasyukevich, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 76 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] données BeiDou [Termes IGN] erreur de phase [Termes IGN] fréquence multiple [Termes IGN] modèle de simulation [Termes IGN] phase GNSS [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement par BeiDou [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Termes IGN] retard ionosphèrique [Termes IGN] trajet multiple Résumé : (auteur) Typically, navigation software processes global navigation satellite system (GNSS) phase observables along with the code observables to achieve high-precision positioning. However, the unmodeled code-related errors, typically multipath effects, may deteriorate the positioning performance. Such effects are well known for the second generation BeiDou navigation satellite system (BDS-2). To prevent this adverse effect on the state-of-the-art positioning technique, namely integer ambiguity resolution-enabled precise point positioning (PPP-RTK), we propose a multi-frequency phase-only PPP-RTK model. This model excludes the code observables and addresses the rank deficiency problem underlying the phase observation equations at the undifferenced and uncombined level. To verify the model, we collect five-day triple-frequency BDS 30-s data from a network of seven reference stations (about 112 km apart) to estimate the products on the network side. Based on these products, we conduct simulated dynamic positioning at a user station to test the phase-only PPP-RTK model and compare it with the customary code-plus-phase (CPP) model. The results show that the satellite phase biases, existing only at the third frequency, have a precision of better than two centimeters, while the precision of the satellite clock and ionospheric delay is better than eight centimeters. Due to the strong correlation between individual corrections, it is necessary to assess the quality of combined products, including the satellite clock, satellite phase bias and ionospheric delay, the precision of which is several millimeters to two centimeters, which is sufficiently precise for user positioning. Regarding BDS-2 positioning, the time-to-first-fix (TTFF) of the CPP PPP-RTK is 12 epochs, while it is only three epochs for the phase-only PPP-RTK. The reason why the CPP model underperforms the phase-only model is that the BDS-2 data collected are subject to notable code multipath. We show that the code multipath in the third-generation BDS (BDS-3) data is mild, so the CPP PPP-RTK achieves instantaneous centimeter-level positioning with a TTFF of one epoch. The BDS-3 phase-only PPP-RTK obtains virtually the same positioning results, but the TTFF is two epochs. When combining BDS-2 with BDS-3, the TTFF of both models remains unchanged compared to that of the BDS-3 solutions, implying that ambiguity resolution based on the stronger dual-system CPP model is robust to the BDS-2 code multipath. However, the ambiguity-float solution of the CPP PPP-RTK is adversely affected by the code multipath and requires 43 epochs to convergence, while its phase-only counterpart needs 36 epochs. Numéro de notice : A2022-377 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01263-x Date de publication en ligne : 10/05/2022 En ligne : https://doi.org/10.1007/s10291-022-01263-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100637 [article]

GNSS observable-specific phase biases for all-frequency PPP ambiguity resolution / Jianghui Geng in Journal of geodesy, vol 96 n° 2 (February 2022)  

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GNSS/INS Kalman filter integrity monitoring with uncertain time correlated error processes / Omar Garcia Crespillo (2022)  

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Multi-frequency quadrifilar helix antennas for cm-accurate GNSS positioning / Lambert Wanninger in Journal of applied geodesy, vol 16 n° 1 (January 2022)  

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Estimation and analysis of GPS inter-fequency clock biases from long-term triple-frequency observations / Fan Zhang in GPS solutions, vol 25 n° 4 (October 2021)  

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Estimation of code observation-specific biases (OSBs) for the modernized multi-frequency and multi-GNSS signals: an undifferenced and uncombined approach / Teng Liu in Journal of geodesy, vol 95 n° 8 (August 2021)  

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Impact of the third frequency GNSS pseudorange and carrier phase observations on rapid PPP convergences / Jiang Guo in GPS solutions, vol 25 n° 2 (April 2021)  

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A multi-frequency and multi-GNSS method for the retrieval of the ionospheric TEC and intraday variability of receiver DCBs / Min Li in Journal of geodesy, vol 94 n° 10 (October 2020)  

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An assessment of wide-lane ambiguity resolution methods for multi-frequency multi-GNSS precise point positioning / Viet Duong in Survey review, vol 52 n° 374 (August 2020)  

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Effect of spatial correlation on the performances of modernized GPS and Galileo in relative positioning / Noureddine Kheloufi in Geodesy and cartography, vol 46 n° 2 (July 2020)  

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Performance of Galileo precise time and frequency transfer models using quad-frequency carrier phase observations / Pengfei Zhang in GPS solutions, vol 24 n° 2 (April 2020)  

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