Phase Center Corrections for BDS IGSO and MEO Satellites in IGb14 and IGSR3 Frame

As pre-launch antenna calibrations are not available for GPS and GLONASS satellites, the high correlation between the terrestrial scale and phase center offset (PCO) prevents a reliable estimation of the terrestrial scale with GNSS (Global Navigation Satellite System) technology. Fortunately, the ground calibrated PCO values for Galileo, BeiDou navigation satellite system (BDS), and QZSS have been released, making a reliable estimation of the terrestrial scale with GNSS possible. In the third reprocess (repro3) of International GNSS Service (IGS), the terrestrial scale derived with Galileo, has been used. To evaluate the consistency of the terrestrial scale derived from the BDS-released PCOs as well as Galileo-released ones, and to incorporate BDS into IGS repro3 as well as operational legacy analysis, the phase center variations (PCV) and PCO for BDS medium earth orbit (MEO) and inclined geostationary orbit (IGSO) satellites are estimated to be consistent with GPS/GLONASS antenna offsets in two frames, i.e., IGb14 and IGS R3, considering robot calibrations of the ground receiver antenna models for BDS released by Geo++. We observe that the average offset of Z-PCOs achieves +98.8 mm between BDS official released and the estimated PCOs in IGb14 frame for BDS-3 MEO satellites, whereas the average offset for Z-PCO is about +174.1 mm (about −1.27 ppb at the height of BDS MEO satellites) between the solutions in IGSR3 and IGb14 frame. The phase center solutions are evaluated with orbit boundary disclosures (OBD) as well as the global station coordinates. The orbit consistency benefits from the PCO/PCV estimates, particularly for BDS-2 MEO satellites, of which the 3D RMS (root mean square) OBD is reduced by 50%, whereas 3D OBD achieves about 90.0 mm for BDS-3 MEO satellites. Moreover, the scale bias between BDS-derived station coordinates and IGS legacy solutions in IGb14 frame is reduced from +0.446 ± 0.153 ppb to +0.012 ± 0.112 ppb using PCO/PCV estimates in IGb14, instead of the BDS official released values. Additionally, the residuals of the BDS-derived station heights (after the Helmert transformation) are slightly reduced from 9.65 to 8.62 mm. On the other hand, about +0.226 ± 0.175 ppb is observed between BDS-only coordinate solutions derived from PCO/PCV estimates in IGSR3 frame and the IGS repro3 initial combination. These results demonstrate that the scale inconsistency derived from BDS and Galileo released PCOs is about +1.854 ± 0.191 ppb, and a good consistency of PCO/PCC estimates for BDS in IGb14 and IGSR3 frame with other systems of GPS/ GLONASS antenna offsets is achieved.

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Centro de Análise Sirgas - IBGE: novas estratégias de processamento e combinação, e a influência da mudança do referencial global nos resultados

Boletim de Ciências Geodésicas ◽

10.1590/s1982-21702012000100004 ◽

2012 ◽

Vol 18 (1) ◽

pp. 63-85

Author(s):

Sonia Maria Alves Costa ◽

Alberto Luis Da Silva ◽

Marco Aurélio De Almeida Lima ◽

Newton José De Moura Júnior

Keyword(s):

Global Navigation Satellite System ◽

Satellite System ◽

Navigation Satellite ◽

International Gnss Service ◽

Global Navigation ◽

Global Navigation Satellite

Atualmente, o SIRGAS (Sistema de Referência Geocêntrico para as Américas) é realizado por uma rede GNSS (Global Navigation Satellite System) permanente denominada SIRGAS-CON, com cerca de 240 estações em funcionamento permanente, distribuídas na América do Sul, Central e Caribe. Os Centros de Análise SIRGAS foram estabelecidos com a finalidade de determinar sistematicamente as coordenadas das estações SIRGAS-CON, seguindo padrões estabelecidos internacionalmente, a fim de apoiar a manutenção do sistema e as atividades do Grupo de Trabalho SIRGAS-GT I (Sistema de Referência). Desde agosto de 2008 a Coordenação de Geodésia do Instituto Brasileiro de Geografia e Estatística-IBGE assumiu oficialmente as atividades de um Centro de Análise. Este é um trabalho cuja dedicação é crescente uma vez que o número de estações no continente Sul Americano vem aumentando rapidamente nos últimos anos. Desta atividade diária são geradas dentre outros resultados, as séries temporais das coordenadas de cada estação, possibilitando assim a determinação dos deslocamentos das estações em função da movimentação da crosta terrestre, os movimentos locais como subsidência e/ou soerguimento crustal, causados por fenômenos naturais, como por exemplo, terremotos, além de efeitos sazonais causados por fatores diversos. Paralelamente a atividade de processamento dos dados GNSS, o IBGE também realiza semanalmente a combinação das soluções semanais dos nove Centros de Processamento SIRGAS. Esta combinação tem por objetivo comparar os resultados com os obtidos pelo DGFI (Deutsches Geodätisches Forschungsinstitut), o qual disponibiliza a solução final semanal da rede SIRGAS-CON. Por se tratar de resultados precisos, a mudança em alguma informação no processamento pode acarretar alterações nas coordenadas determinadas e, conseqüentemente, descontinuidades nas séries temporais de cada estação. Recentemente, em 17 de abril de 2011 (semana GPS 1632), as órbitas (finais e rápidas), as correções dos relógios dos satélites e o modelo de calibração das antenas disponibilizado pelo International GNSS Service - IGS, passaram a estar referidos à nova realização do IGS, denominada IGS08. Conseqüentemente, a partir dessa data, os processamentos GPS que utilizam os produtos IGS terão seus resultados referidos a este novo sistema de referência, o que poderá acarretar descontinuidades nas coordenadas. O objetivo desse trabalho é apresentar a estratégia de processamento atualmente em operação, bem com uma nova estratégia visando à melhoria dos resultados. Outro objetivo é apresentar alguns resultados do processamento e combinação semanal realizados pelo IBGE, bem como esclarecer as alterações ocorridas com a adoção da nova versão da Rede de Referência Global para soluções GNSS, o IGS08 e uma análise preliminar da conseqüência desta mudança.

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A Comparative Study for Performance Analysis of Kinematic Multi-Constellation GNSS PPP in Dynamic Environment

Journal of Marine Science and Engineering ◽

10.3390/jmse8070514 ◽

2020 ◽

Vol 8 (7) ◽

pp. 514

Author(s):

Serdar Erol

Keyword(s):

Global Navigation Satellite System ◽

Test Procedure ◽

Dynamic Environment ◽

Satellite System ◽

Research Centre ◽

Navigation Satellite ◽

Post Processing ◽

International Gnss Service ◽

Global Navigation ◽

Global Navigation Satellite

This case study aims to investigate the effect of different Multi-GNSS EXperiment (MGEX) precise products provided by International GNSS Service (IGS) Analysis Centers (ACs) on post-processing kinematic Precise Point Positioning (PPP) accuracy performance with different satellite system combinations in a dynamic environment. Within this frame, a test was carried out in a lake and kinematic data were collected over 6 h at 1 Hz rate from the available Global Navigation Satellite System (GNSS) constellations with the geodetic-grade receiver fixed on a marine vehicle for bathymetric mapping. PPP-derived coordinates were determined by a commercial GNSS post-processing software with different processing approaches as GPS (Global Positioning System)-only, GPS+GLObal’naya NAvigatsionnaya Sputnikovaya Sistema (GLONASS), GPS+GLONASS+European Global Navigation Satellite System (Galileo), GPS+GLONASS+Chinese Global Navigation Satellite System (BeiDou), and GPS+GLONASS+Galileo+BeiDou. The PPP coordinates were then compared to the reference coordinates obtained from the post-processed carrier phase-based differential kinematic solutions. In general, the results showed that the kinematic multi-constellation GNSS PPP technique could provide positioning accuracy from cm to decimeter level as depending on the collected data constellations and used precise products in the processing. Among all solutions, the GPS+GLONASS+Galileo+BeiDou combination with German Research Centre for Geosciences (GFZ)’s precise products presented the best multi-GNSS PPP performance, rather than the other combinations and quad-constellation alternatives using different precise products. In this study, the test procedure and the obtained results are given in detail.

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Impact of Using GPS L2 Receiver Antenna Corrections for the Galileo E5a Frequency on Position Estimates

Sensors ◽

10.3390/s20195536 ◽

2020 ◽

Vol 20 (19) ◽

pp. 5536

Author(s):

Andrzej Araszkiewicz ◽

Damian Kiliszek

Keyword(s):

Satellite System ◽

Differential Analysis ◽

International Gnss Service ◽

Phase Center ◽

Significant Difference ◽

Anechoic Chambers ◽

Antenna Phase ◽

Antenna Phase Center ◽

Global Navigation Satellite ◽

The Impact

Knowledge of Global Navigation Satellite System (GNSS) antenna phase center variations plays a key role in precise positioning. Proper modeling is achieved by accessing antenna phase center corrections, which are determined in the calibration process. For most receiver antenna types, the International GNSS Service provides such corrections for two GPS and GLONASS carrier signals. In the case of Galileo, access to phase center corrections is difficult; only antennas calibrated in the anechoic chambers have available corrections for Galileo frequencies. Hence, in many of the studies, GPS-dedicated corrections are used for these Galileo frequencies. Differential analysis was conducted in this study to evaluate the impact of such change. In total, 25 stations belonging to the EUREF Permanent Network and equipped with individual calibrated antennas were the subject of this research. The results for both the absolute and relative positioning methods are clear: using GPS L2 corrections for Galileo E5a frequency causes a bias in the estimated height of almost 8 mm. For the horizontal component, a significant difference can be noticed for only one type of antenna.

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Height Variation Depending on the Source of Antenna Phase Centre Corrections: LEIAR25.R3 Case Study

Sensors ◽

10.3390/s19184010 ◽

2019 ◽

Vol 19 (18) ◽

pp. 4010 ◽

Cited By ~ 3

Author(s):

Andrzej Araszkiewicz ◽

Damian Kiliszek ◽

Anna Podkowa

Keyword(s):

Satellite System ◽

International Gnss Service ◽

Phase Center ◽

Antenna Phase ◽

Antenna Phase Center ◽

The Stability ◽

Global Navigation Satellite ◽

Antenna Phase Centre ◽

The Impact

In this study, we compared two sets of antenna phase center corrections for groups of the same type of antenna mounted at the continuously operating global navigation satellite system (GNSS) reference stations. The first set involved type mean models provided by the International GNSS Service (release igs08), while the second set involved individual models developed by Geo++. Our goal was to check which set gave better results in the case of height estimation. The paper presents the differences between models and their impact on resulting height. Analyses showed that, in terms of the stability of the determined height, as well as its variability caused by increasing the facade mask, both models gave very similar results. Finally, we present a method for how to estimate the impact of differences in phase center corrections on height changes.

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Potencialidades do PPP no Software Bernese com Compatibilizações de Sistemas Geodésicos de Referência e de Tempo

Revista Brasileira de Cartografia ◽

10.14393/rbcv71n3-47483 ◽

2019 ◽

Vol 71 (3) ◽

pp. 726-755

Author(s):

Franciele Lúcia Silva Braga ◽

William Rodrigo Dal Poz

Keyword(s):

Global Navigation Satellite System ◽

Satellite System ◽

Navigation Satellite ◽

International Gnss Service ◽

Global Navigation ◽

Global Navigation Satellite

O Software Bernese GNSS (BSW) é um conjunto de pacotes de processamento de observáveis GNSS (Global Navigation Satellite System) de alto desempenho, que proporciona estimativas com alta acurácia, e flexibilidade em suas aplicações. Uma destas funcionalidades é a automatização de scripts que realizam o Posicionamento por Ponto Preciso (PPP). O objetivo deste trabalho é analisar as potencialidades do PPP no BSW. Para alcançar esse propósito foram estimadas as coordenadas de 90 estações da RBMC (Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS) no BSW e no serviço IBGE-PPP online, referenciadas a atual realização do International GNSS Service, o IGS14, na época dos dados. As coordenadas estimadas foram comparadas com as coordenadas de referência das estações (SIRGAS2000, época 2000,40), de três formas distintas: 1. Referenciais e épocas incompatíveis; 2. Compatibilização apenas dos referenciais; e 3. Referenciais e épocas compatíveis. As acurácias das coordenadas reduziram no processo de compatibilização de referenciais. Como esperado, o fator predominante na alteração das coordenadas planimétricas se refere à sua evolução temporal. Ademais, as acurácias planimétricas e altimétricas apresentaram estatísticas descritivas similares ao nível do milímetro, evidenciando a potencialidade do BSW no PPP.

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Accuracy Analysis of GNSS Hourly Ultra-Rapid Orbit and Clock Products from SHAO AC of iGMAS

Remote Sensing ◽

10.3390/rs13051022 ◽

2021 ◽

Vol 13 (5) ◽

pp. 1022

Author(s):

Qinming Chen ◽

Shuli Song ◽

Weili Zhou

Keyword(s):

Real Time ◽

Satellite System ◽

High Accuracy ◽

Observation Data ◽

Navigation Satellite ◽

International Gnss Service ◽

Observation Session ◽

New Strategy ◽

Analysis Center ◽

Global Navigation Satellite

With the development of the global navigation satellite system(GNSS), the hourly ultra-rapid products of GNSS are attracting more attention due to their low latency and high accuracy. A new strategy and method was applied by the Shanghai Astronomical Observatory (SHAO) Analysis Center (AC) of the international GNSS Monitoring and Assessment Service (iGMAS) for generating 6-hourly and 1-hourly GNSS products, which mainly include the American Global Positioning System (GPS), the Russian Global’naya Navigatsionnaya Sputnikova Sistema (GLONASS), the European Union’s Galileo, and the Chinese BeiDou navigation satellite system (BDS). The 6-hourly and 1-hourly GNSS orbit and clock ultra-rapid products included a 24-h observation session which is determined by 24-h observation data from global tracking stations, and a 24-h prediction session which is predicted from the observation session. The accuracy of the 1-hourly orbit product improved about 1%, 31%, 13%, 11%, 23%, and 9% for the observation session and 18%, 43%, 45%, 34%, 53%, and 15% for the prediction session of GPS, GLONASS, Galileo, BDS Medium Earth Orbit (MEO), Inclined Geosynchronous Orbit (IGSO), and GEO orbit, when compared with reference products with high accuracy from the International GNSS service (IGS).The precision of the 1-hourly clock products can also be seen better than the 6-hourly clock products. The accuracy and precision of the 6-hourly and 1-hourly orbit and clock verify the availability and reliability of the hourly ultra-rapid products, which can be used for real-time or near-real-time applications, and show encouraging prospects.

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Estimation and Analysis of the Observable-Specific Code Biases Estimated Using Multi-GNSS Observations and Global Ionospheric Maps

Remote Sensing ◽

10.3390/rs13163096 ◽

2021 ◽

Vol 13 (16) ◽

pp. 3096

Author(s):

Min Li ◽

Yunbin Yuan

Keyword(s):

Satellite System ◽

Navigation Satellite ◽

International Gnss Service ◽

Chinese Academy Of Sciences ◽

Code Bias ◽

Global Ionospheric Maps ◽

German Aerospace ◽

Global Navigation Satellite ◽

Similar Code ◽

Academy Of Sciences

Observable-specific bias (OSB) parameterization allows observation biases belonging to various signal types to be flexibly addressed in the estimation of ionosphere and global navigation satellite system (GNSS) clock products. In this contribution, multi-GNSS OSBs are generated by two different methods. With regard to the first method, geometry-free (GF) linear combinations of the pseudorange and carrier-phase observations of a global multi-GNSS receiver network are formed for the extraction of OSB observables, and global ionospheric maps (GIMs) are employed to correct ionospheric path delays. Concerning the second method, satellite and receiver OSBs are converted directly from external differential code bias (DCB) products. Two assumptions are employed in the two methods to distinguish satellite- and receiver-specific OSB parameters. The first assumption is a zero-mean condition for each satellite OSB type and GNSS signal. The second assumption involves ionosphere-free (IF) linear combination signal constraints for satellites and receivers between two signals, which are compatible with the International GNSS Service (IGS) clock product. Agreement between the multi-GNSS satellite OSBs estimated by the two methods and those from the Chinese Academy of Sciences (CAS) is shown at levels of 0.15 ns and 0.1 ns, respectively. The results from observations spanning 6 months show that the multi-GNSS OSB estimates for signals in the same frequency bands may have very similar code bias characteristics, and the receiver OSB estimates present larger standard deviations (STDs) than the satellite OSB estimates. Additionally, the variations in the receiver OSB estimates are shown to be related to the types of receivers and antennas and the firmware version. The results also indicate that the root mean square (RMS) of the differences between the OSBs estimated based on the CAS- and German Aerospace Center (DLR)-provided DCB products are 0.32 ns for the global positioning system (GPS), 0.45 ns for the BeiDou navigation satellite system (BDS), 0.39 ns for GLONASS and 0.22 ns for Galileo.

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Estimation of fractional cycle bias for GPS/BDS-2/Galileo based on international GNSS monitoring and assessment system observations using the uncombined PPP model

Satellite Navigation ◽

10.1186/s43020-021-00039-x ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Jin Wang ◽

Qin Zhang ◽

Guanwen Huang

Keyword(s):

Estimation Method ◽

Satellite Orbit ◽

Satellite System ◽

Assessment System ◽

Navigation Satellite ◽

Dual Frequency ◽

Fractional Cycle Bias ◽

The Stability ◽

High Consistency ◽

Global Navigation Satellite

AbstractThe Fractional Cycle Bias (FCB) product is crucial for the Ambiguity Resolution (AR) in Precise Point Positioning (PPP). Different from the traditional method using the ionospheric-free ambiguity which is formed by the Wide Lane (WL) and Narrow Lane (NL) combinations, the uncombined PPP model is flexible and effective to generate the FCB products. This study presents the FCB estimation method based on the multi-Global Navigation Satellite System (GNSS) precise satellite orbit and clock corrections from the international GNSS Monitoring and Assessment System (iGMAS) observations using the uncombined PPP model. The dual-frequency raw ambiguities are combined by the integer coefficients (4,− 3) and (1,− 1) to directly estimate the FCBs. The details of FCB estimation are described with the Global Positioning System (GPS), BeiDou-2 Navigation Satellite System (BDS-2) and Galileo Navigation Satellite System (Galileo). For the estimated FCBs, the Root Mean Squares (RMSs) of the posterior residuals are smaller than 0.1 cycles, which indicates a high consistency for the float ambiguities. The stability of the WL FCBs series is better than 0.02 cycles for the three GNSS systems, while the STandard Deviation (STD) of the NL FCBs for BDS-2 is larger than 0.139 cycles. The combined FCBs have better stability than the raw series. With the multi-GNSS FCB products, the PPP AR for GPS/BDS-2/Galileo is demonstrated using the raw observations. For hourly static positioning results, the performance of the PPP AR with the three-system observations is improved by 42.6%, but only 13.1% for kinematic positioning results. The results indicate that precise and reliable positioning can be achieved with the PPP AR of GPS/BDS-2/Galileo, supported by multi-GNSS satellite orbit, clock, and FCB products based on iGMAS.

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Performance evaluation of multi-GNSSs navigation in super synchronous transfer orbit and geostationary earth orbit

Satellite Navigation ◽

10.1186/s43020-021-00036-0 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Tao Shi ◽

Xuebin Zhuang ◽

Liwei Xie

Keyword(s):

Global Navigation Satellite System ◽

Autonomous Navigation ◽

Satellite System ◽

Earth Orbit ◽

Navigation Satellite ◽

Geostationary Earth Orbit ◽

Beidou Navigation Satellite System ◽

Transfer Orbit ◽

High Orbit ◽

Global Navigation Satellite

AbstractThe autonomous navigation of the spacecrafts in High Elliptic Orbit (HEO), Geostationary Earth Orbit (GEO) and Geostationary Transfer Orbit (GTO) based on Global Navigation Satellite System (GNSS) are considered feasible in many studies. With the completion of BeiDou Navigation Satellite System with Global Coverage (BDS-3) in 2020, there are at least 130 satellites providing Position, Navigation, and Timing (PNT) services. In this paper, considering the latest CZ-5(Y3) launch scenario of Shijian-20 GEO spacecraft via Super-Synchronous Transfer Orbit (SSTO) in December 2019, the navigation performance based on the latest BeiDou Navigation Satellite System (BDS), Global Positioning System (GPS), Galileo Navigation Satellite System (Galileo) and GLObal NAvigation Satellite System (GLONASS) satellites in 2020 is evaluated, including the number of visible satellites, carrier to noise ratio, Doppler, and Position Dilution of Precision (PDOP). The simulation results show that the GEO/Inclined Geo-Synchronous Orbit (IGSO) navigation satellites of BDS-3 can effectively increase the number of visible satellites and improve the PDOP in the whole launch process of a typical GEO spacecraft, including SSTO and GEO, especially for the GEO spacecraft on the opposite side of Asia-Pacific region. The navigation performance of high orbit spacecrafts based on multi-GNSSs can be significantly improved by the employment of BDS-3. This provides a feasible solution for autonomous navigation of various high orbit spacecrafts, such as SSTO, MEO, GEO, and even Lunar Transfer Orbit (LTO) for the lunar exploration mission.

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OutFin, a multi-device and multi-modal dataset for outdoor localization based on the fingerprinting approach

Scientific Data ◽

10.1038/s41597-021-00832-y ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Fahad Alhomayani ◽

Mohammad H. Mahoor

Keyword(s):

Global Navigation Satellite System ◽

Urban Areas ◽

Satellite System ◽

Reference Points ◽

Navigation Satellite ◽

Data Types ◽

Entry Barrier ◽

Promising Alternative ◽

Global Navigation ◽

Global Navigation Satellite

AbstractIn recent years, fingerprint-based positioning has gained researchers’ attention since it is a promising alternative to the Global Navigation Satellite System and cellular network-based localization in urban areas. Despite this, the lack of publicly available datasets that researchers can use to develop, evaluate, and compare fingerprint-based positioning solutions constitutes a high entry barrier for studies. As an effort to overcome this barrier and foster new research efforts, this paper presents OutFin, a novel dataset of outdoor location fingerprints that were collected using two different smartphones. OutFin is comprised of diverse data types such as WiFi, Bluetooth, and cellular signal strengths, in addition to measurements from various sensors including the magnetometer, accelerometer, gyroscope, barometer, and ambient light sensor. The collection area spanned four dispersed sites with a total of 122 reference points. Each site is different in terms of its visibility to the Global Navigation Satellite System and reference points’ number, arrangement, and spacing. Before OutFin was made available to the public, several experiments were conducted to validate its technical quality.

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