Assessment of NeQuick ionospheric model for Galileo single-frequency users

Angrisano, Antonio; Gaglione, Salvatore; Gioia, Ciro; Massaro, Marco; Robustelli, Umberto

doi:10.2478/s11600-013-0116-2

Cited by 30 publications

(17 citation statements)

References 20 publications

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“…It is noted that the accuracy of C07 and C10 is worse than other IGSOs in each direction, which is caused by the inaccurate SRP and the switch model for the yaw-attitude and the normal-attitude in eclipsing seasons. It is pointed out that the inaccurate attitudes can seriously impact on the accuracy of the POD solutions and cause difficulty on the SRP modeling which can also result in significant orbit errors [14]. Other than C07 and C10, other IGSO orbit products have the same accuracy level as BDS MEOs.…”

Section: Bds Orbit Resultsmentioning

confidence: 99%

National BDS Augmentation Service System (NBASS) of China: Progress and Assessment

et al. 2017

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Abstract:In this contribution, the processing strategies of real-time BeiDou System (BDS) precise orbits, clocks, and ionospheric corrections in the National BDS Augmentation Service System (NBASS) are briefly introduced. The Root Mean Square (RMS) of BDS predicted orbits are better than 10 cm in radial and cross-track components, and the accuracy of the BDS real-time clock is better than 0.5 ns for Inclined Geosynchronous Orbit (IGSO) and Mid Earth Orbit (MEO) satellites. The accuracy of BDS Geostationary Earth Orbit (GEO) orbits and clocks are worse than the IGSO and MEO satellites due to its poor geometry conditions. The real-time ionospheric correction is evaluated by cross-validation, and the average accuracy in the vertical direction is about 4 TECU. With these real-time corrections, the overall single and dual-frequency kinematic precise point positioning (PPP) performance in China are evaluated in terms of positioning accuracy at the 95% confidence level and convergence time.The BDS PPP positioning accuracy shows significant regional characteristics due to the geometry distribution of BDS satellites and the accuracy of ionospheric model in different regions. The BDS dual-frequency PPP positioning accuracy in high-latitude and western fringe region is about 0.5 m and 1.0 m in the horizontal and vertical component, respectively, while the horizontal accuracy is better than 0.2 m and the vertical accuracy is better than 0.3 m in the midlands. The convergence time of the BDS PPP is much longer than the GPS PPP and it needs more than 60 min to achieve the accuracy better than 10 cm in both horizontal and vertical directions for dual-frequency PPP. Similar with dual-frequency PPP, the positioning accuracy of the BDS single-frequency PPP in the fringe region is worse than other regions. The positioning in the midlands can achieve 0.5 m in horizontal component and 1.0 m in the vertical component. In addition, when GPS and BDS are combined, the positioning performance of both single-frequency and dual-frequency PPP can be greatly improved.

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Section: Bds Orbit Resultsmentioning

confidence: 99%

National BDS Augmentation Service System (NBASS) of China: Progress and Assessment

et al. 2017

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“…It uses empirical ionospheric parameters and provides monthly median output (Bidaine and Warnant, 2010). As emphasised by Angrisano et al (2013), an ionospheric correction model has to have a daily output. For Galileo SF, NeQuick G (Galileo), the adaptation of the NeQuick model to real time, is governed by the effective ionisation level parameter called Az (Eq.…”

Section: Nequick Modelmentioning

confidence: 99%

“…These systems broadcast ionospheric correction messages to the GNSS receiver according to its localisation. This technique, which can be used by both single-and dual-frequency receivers, requires more complex and expensive receivers (Angrisano et al, 2013). The easiest way for single-frequency (SF) receivers to compensate for the ionospheric error is to rely on an ionospheric correction algorithm based on existing models such as the Klobuchar and NeQuick models (Aragón-Ángel and Zürn, 2006;European GNSS, 2015).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the NeQuick model performance under different geomagnetic conditions over South Africa during the ascending phase of the solar cycle (2009–2012)

et al. 2018

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Abstract. In order to provide a scientific base to the NeQuick characterisation under disturbed conditions, the comparison of its performance for quiet and storm days is investigated in the southern mid-latitude. This investigation was realised using the two versions of the NeQuick model which were adapted to local and storm-specific response by using the critical frequency of the F2 layer (foF2) and the propagation factor (M(3000)F2) derived from three South African ionosonde measurements, Hermanus (34.40∘ S, 19.20∘ E), Grahamstown (33.30∘ S, 26.50∘ E) and Louisvale (28.50∘ S, 21.20∘ E). The number of free electrons contained within a 1 m squared column section known as total electron content (TEC) is a widely used ionospheric parameter to estimate its impact on the radio signal passing through. In this study, the TEC derived from the adapted NeQuick version is compared with observed TEC derived from Global Navigation Satellite System (GNSS) data from co-located or nearby GNSS dual-frequency receivers. The Hermanus K-index is used to select all the disturbed days (K-index ≥ 5) upon moving from low to high solar activity (from 2009 to 2012). For each disturbed day, a quiet reference day of the same month was chosen for the investigation. The study reveals that the NeQuick model shows similar reliability for both magnetic quiet and disturbed conditions, but its accuracy is affected by the solar activity. The model is much better for moderate solar activity epochs (2009 and 2010), while it exhibits a discrepancy with observations during high solar activity epochs. For instance in Hermanus, the difference between GPS TEC and NeQuick TEC (ΔTEC) is generally lower than 10 TECu in 2009, and it sometimes reaches 20 TECu in 2011 and 2012. It is also noticed that NeQuick 2 is more accurate than NeQuick 1, with an improvement in TEC estimation more significant for the high solar activity epochs. The improvement realised in the latest version of NeQuick is more than 15 % and sometimes reaches 50 %. Keywords. Ionosphere (mid-latitude ionosphere; modelling and forecasting)

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“…The assessment and comparison of broadcast ionospheric models are investigated in [ 19 ]. The improvements brought by NeQuick-G with respect to the Klobuchar models in the range and position domains were presented in [ 20 ]. The analysis was performed for different stations around the globe.…”

Section: Introductionmentioning

confidence: 99%

NeQuick-G and Android Devices: A Compromise between Computational Burden and Accuracy

Gioia

Borio

2020

Sensors

Self Cite

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Ionospheric delay is one of the largest errors affecting Global Navigation Satellite System (GNSS) positioning in open-sky conditions, and different methods are currently available for mitigating ionospheric effects including dual-frequency measurements and corrections from augmentation systems. For single-frequency standalone receivers, the most widely used approach to correct ionospheric delays is to rely on a model. In this respect, Klobuchar and NeQuick-G Ionospheric Correction Algorithm (ICAs) are the approaches adopted by GPS and Galileo, respectively. While the latter outperforms the Klobuchar model, it requires a significantly higher computational load, which can limit its exploitation in some market segments such as smartphones. In order to foster adoption of the NeQuick-G model in this type of device, a smart application of NeQuick-G is proposed. The solution relies on the assumption that ionospheric delays are practically constant over short time intervals. Thus, the update rate of the ionospheric correction computation can be significantly reduced. This solution was implemented, tested, and evaluated using real data collected with a static smartphone in an ad hoc set-up. The impact of reducing the ionospheric correction update rate has been evaluated in terms of processing time, of ionospheric correction deviations and in the Ranging Error (RE) and position domains. The analysis shows that a significant reduction of the processing time can be obtained with negligible degradation of the navigation solution.

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Assessment of NeQuick ionospheric model for Galileo single-frequency users

Cited by 30 publications

References 20 publications

National BDS Augmentation Service System (NBASS) of China: Progress and Assessment

National BDS Augmentation Service System (NBASS) of China: Progress and Assessment

Evaluation of the NeQuick model performance under different geomagnetic conditions over South Africa during the ascending phase of the solar cycle (2009–2012)

NeQuick-G and Android Devices: A Compromise between Computational Burden and Accuracy

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