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Undifferenced and uncombined GNSS time and frequency transfer with integer ambiguity resolution / Xiaolong Mi in Journal of geodesy, vol 97 n° 2 (February 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 2 (February 2023) . - n° 13 Titre : Undifferenced and uncombined GNSS time and frequency transfer with integer ambiguity resolution Type de document : Article/Communication Auteurs : Xiaolong Mi, Auteur ; Baocheng Zhang, Auteur ; Ahmed El-Mowafy, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 13 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] modèle ionosphérique [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement ponctuel précis [Termes IGN] résolution d'ambiguïté [Termes IGN] retard ionosphèrique [Termes IGN] temps-fréquence Résumé : (auteur) Precise point positioning (PPP) has been a competitive global navigation satellite system (GNSS) technique for time and frequency transfer. However, the classical PPP is usually based on the ionosphere-free combination of dual-frequency observations, which has limited flexibility in the multi-frequency scenario. More importantly, the unknown integer ambiguities are not restored to the integer nature, making the advantage of high-precision carrier phase observations underutilized. In this contribution, using the undifferenced and uncombined (UDUC) observations, we derive the time and frequency transfer model suitable for multi-constellation and multi-frequency scenarios. Notably, in short- and medium-baseline time and frequency transfer, the ionosphere-fixed and ionosphere-weighted UDUC models are derived, respectively, by making full use of the single-differenced (SD) ionospheric constraints. The proposed model can be applied to short-, medium- and long-baseline time and frequency transfer. The ambiguities are solved in a double-differenced (DD) form and can thus be restored to integers. To verify the feasibility of the model, GPS data from several time laboratories were collected, and the performance of the time and frequency transfer were analyzed with different baseline lengths. The results showed that the ionosphere-fixed and ionosphere-weighted UDUC models with integer ambiguity resolution could improve the frequency stability by 25–60% and 9–30% at an averaging time of several tens of seconds to 1 day for short- and medium-baseline, respectively. Concerning the long-baseline, the UDUC model is 10–25% more stable than PPP for averaging time below a few thousands second and over 1 day. Numéro de notice : A2022-613 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01689-8 Date de publication en ligne : 06/02/2023 En ligne : https://doi.org/10.1007/s00190-022-01689-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102677 [article]

Autonomous coordinate establishment of local reference frames for ground-based positioning systems without known points / Tengfei Wang in Journal of geodesy, vol 97 n° 1 (January 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 1 (January 2023) . - n° 4 Titre : Autonomous coordinate establishment of local reference frames for ground-based positioning systems without known points Type de document : Article/Communication Auteurs : Tengfei Wang, Auteur ; Zheng Yao, Auteur ; Mingquan Lu, Auteur Année de publication : 2023 Article en page(s) : n° 4 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] ambiguïté entière [Termes IGN] auto-étalonnage [Termes IGN] mesurage de phase [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement par GNSS [Termes IGN] pseudolite [Termes IGN] récepteur [Termes IGN] signal GPS Résumé : (auteur) Ground-based positioning systems (GBPSs) can serve as a supplement and backup to global navigation satellite systems. GBPSs are known for their low cost and high flexibility, but most of them have difficulty in achieving rapid deployment and operation, since the coordinates of transmitters rely on external precise measurements. Several existing self-calibration methods based on carrier phase measurements require known points of GBPS transmitters or receivers, which implies dependence on external measurements. This paper proposes an autonomous coordinate establishment (ACE) method without using known reference points for GBPSs. ACE utilizes a kinematic receiver to collect carrier phase measurements and employs a three-step procedure to establish a regional coordinate system. In the first step, ACE uses the properties of matrix structures to decouple generalized ambiguities and coordinates. Then, ACE obtains the rough estimation of the transmitter coordinates via multi-dimensional scaling in the second step. In the third step, ACE refines the estimate by solving a least squares problem which would be difficult to solve without the previous two steps. Numerical simulations and a real-world experiment show that the coordinate estimation of ACE can achieve decimeter to centimeter-level accuracy. The proposed method enables rapid deployment and operation for GBPSs. Numéro de notice : A2023-123 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01687-w Date de publication en ligne : 04/01/2023 En ligne : https://doi.org/10.1007/s00190-022-01687-w Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102499 [article]

High-precision positioning using plane-constrained RTK method in urban environments / Chen Zhuang 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° 540 Titre : High-precision positioning using plane-constrained RTK method in urban environments Type de document : Article/Communication Auteurs : Chen Zhuang, Auteur ; Hongbo Zhao, Auteur ; Yuli He, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 540 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] antenne GNSS [Termes IGN] Chine [Termes IGN] estimateur [Termes IGN] filtre de Kalman [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement par GNSS [Termes IGN] Receiver Autonomous Integrity Monitoring [Termes IGN] résolution d'ambiguïté [Termes IGN] véhicule [Termes IGN] zone urbaine Résumé : (auteur) High-precision positioning methods have drawn great attention in recent years due to the rapid development of smart vehicles as well as automatics driving technology. The Real-Time Kinematic (RTK) technique is a mature tool to achieve centimeter-level positioning accuracy in open-sky areas. However, the users who drive under dense urban conditions are always confronted with harsh global navigation satellite system (GNSS) environments. Skyscrapers and overpasses block the signals and reduce the number of visible satellites, making it difficult to achieve continuous and precise positioning. Considering that the road is relatively smooth in most urban areas, vehicles are expected to travel on the same plane when they are close to each other. The road plane information is a promising candidate to enhance the performance of the RTK method in constrained environments. In this paper, we propose a plane-constrained RTK (PCRTK) method using the positioning information from cooperative vehicles. In a vehicle-to-vehicle (V2V) network, the positions of cooperative vehicles are used to fit a road plane for the target vehicle. The parameters of the plane fitting are treated as new measurements to enhance the performance of the float estimator. The relationship between the plane parameters and the state of the estimator is derived in our study. To validate the performance of the proposed method, several experiments with a four-vehicle fleet were carried out in open-sky areas and dense urban areas in Beijing, China. Simulations and experimental results show that the proposed method can take advantage of the plane constraint and obtain more accurate positioning results compared to the traditional RTK method. Numéro de notice : A2020-917 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.540 Date de publication en ligne : 14/07/2022 En ligne : https://doi.org/10.33012/navi.540 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102444 [article]

A method to determine secondary codes and carrier phases of short snapshot signals / Xiao Liu 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° 541 Titre : A method to determine secondary codes and carrier phases of short snapshot signals Type de document : Article/Communication Auteurs : Xiao Liu, Auteur ; Pau Closas, Auteur ; Adria Gusi-Amigó, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 541 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] ambiguïté entière [Termes IGN] phase [Termes IGN] positionnement cinématique en temps réel [Termes IGN] signal GNSS [Termes IGN] temps instantané Résumé : (auteur) Recently, the Snapshot Real-Time Kinematic (SRTK) technique was demonstrated, which aims at achieving high accuracy navigation solutions with a very short signal collection. The main challenge in implementing SRTK is the generation of valid carrier-phase measurements, which relies on a data bit ambiguity (DBA) resolution process. For pilot signals, this step is equivalent to the correct selection of secondary code indexes (SCIs) from the ambiguous sets obtained from a multi-hypotheses (MH) acquisition process. Currently, SCI ambiguities are solved independently for each satellite. However, this method is ineffective when the snapshot signal is relatively short. In order to tackle this problem, this article proposes a new method that makes use of assistance data and processes information from all satellites to jointly solve the DBA issue. This new method is shown to be more effective in determining the correct SCI and enabling valid snapshot carrier-phase measurements, largely expanding the scope of high-accuracy snapshot positioning. Numéro de notice : A2022-868 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.541 Date de publication en ligne : 21/04/2022 En ligne : https://doi.org/10.33012/navi.541 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102161 [article]

PPP-RTK: from common-view to all-in-view GNSS networks / Baocheng Zhang in Journal of geodesy, vol 96 n° 12 (December 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 12 (December 2022) . - n° 102 Titre : PPP-RTK: from common-view to all-in-view GNSS networks Type de document : Article/Communication Auteurs : Baocheng Zhang, Auteur ; Pengyu Hou, Auteur ; Robert Odolinski, Auteur Année de publication : 2022 Article en page(s) : n° 102 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] erreur de phase [Termes IGN] positionnement cinématique en temps réel [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] précision du positionnement [Termes IGN] résolution d'ambiguïté Résumé : (auteur) Integer ambiguity resolution-enabled precise point positioning (PPP), otherwise known as PPP real-time kinematic (PPP-RTK), recovers the integer nature of ambiguities at a user receiver by delivering the satellite phase biases (SPBs) estimated from a global navigation satellite system (GNSS) network. Due to the rank-deficiency existing between the satellite and receiver phase biases and the ambiguities, the formulation of PPP-RTK model needs to choose a set of unknown parameters as the datum (or the S-basis). Despite the fact that there are non-unique datum choices, one prefers a PPP-RTK model where the estimable SPBs contain a minimum number of datum ambiguities. We will show that otherwise there will be discontinuities occurring in datum ambiguities that will lead to unfavorable jumps in the estimated SPBs and frequent ambiguity resolution (re-)initialization on the user side. For this to occur one normally restricts to a common-view (CV) network, where the satellites are commonly visible to all receivers involved, and constructs the PPP-RTK model by choosing the phase biases and the ambiguities, pertaining to one receiver, as the datum. In doing so the CV model is capable of estimating the SPBs with each bias containing only one datum ambiguity. In this contribution we extend the CV model to an all-in-view (AV) network case where the satellites tracked can differ across receivers, but at least one satellite is commonly visible; this is practical as the network size is normally consisting of baseline lengths of several hundreds of kilometers. Contrary to the CV model, in the AV model the phase biases and the ambiguities pertaining to one satellite is selected as the datum, such that, the number of datum ambiguities entering into the estimable SPBs is always at the minimum as the SPBs are formulated in a between-satellite single-differenced form. The benefits with AV model are that it relieves the stringent satellite visibility as required by the CV model and, at the same time, reduces to the best possible extent any jumps in the estimated SPBs as well as the necessary ambiguity resolution (re-)initialization on the user side. Experiments conducted using multi-GNSS data collected in both CV and AV networks verify that the AV model always outperforms the CV one, as measured by both the time-to-first-fix as well as the positioning accuracy when compared to very precise benchmark coordinates. Numéro de notice : A2022-899 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01693-y Date de publication en ligne : 13/12/2022 En ligne : https://doi.org/10.1007/s00190-022-01693-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102257 [article]

PPP–RTK theory for varying transmitter frequencies with satellite and terrestrial positioning applications / Peter J.G. Teunissen in Journal of geodesy, vol 96 n° 11 (November 2022)  

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An efficient method to compensate receiver clock jumps in real-time precise point positioning / Shaoguang Xu in Remote sensing, vol 14 n° 20 (October-2 2022)  

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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)  

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

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GNSS integer ambiguity posterior probability calculation with controllable accuracy / Zemin Wu in Journal of geodesy, vol 96 n° 8 (August 2022)  

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An accurate train positioning method using tightly-coupled GPS + BDS PPP/IMU strategy / Wei Jiang in GPS solutions, vol 26 n° 3 (July 2022)  

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

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Adaptive Kalman filter for real-time precise orbit determination of low earth orbit satellites based on pseudorange and epoch-differenced carrier-phase measurements / Min Li in Remote sensing, vol 14 n° 9 (May-1 2022)  

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A search step optimization in an ambiguity function-based GNSS precise positioning / Sławomir Cellmer in Survey review, vol 54 n° 383 (March 2022)  

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Vectorial integer bootstrapping: flexible integer estimation with application to GNSS / Peter J.G. Teunissen in Journal of geodesy, vol 95 n° 9 (September 2021)  

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