Fast ionospheric correction using Galileo Az coefficients and the NTCM model

Hoque, Mohammed Mainul; Jakowski, N.; Orús‐Pérez, Raül

doi:10.1007/s10291-019-0833-3

Cited by 30 publications

(27 citation statements)

References 14 publications

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“…These are most obvious in the year of low solar activity, where the model predictions appear to underestimate the actual STEC variation at daytime and low-latitude, i.e., in the vicinity of the ionospheric bulge. A degraded quality of NeQuick-G predictions at low-latitude regions, as compared to other regions, has earlier been noted in comparison of ground-based STEC observations as well as VTEC values from altimetry satellite missions (Hoque et al 2019), which correlates with the present findings for a spaceborne GPS receiver.…”

Section: Slant Tecsupporting

confidence: 85%

“…Slant total electron content (STEC) in NeQuick is obtained by numerical integration of the electron density along the line of sight between the GNSS satellite and receiver. This requires computation and evaluation of the height-dependent electron density profiles above numerous foot points of the signal path and results in a computational effort that notably exceeds that of alternative two-dimensional ionosphere models (Klobuchar 1987, Hoque 2019). On the other hand, the three-dimensional nature of NeQuick imposes no height limitation and extends the range of application from the near-earth environment to spaceborne users.…”

Section: Nequick-g Model Description and Leo Applicationmentioning

confidence: 99%

“…Ionospheric correction parameters a i0 , a i1 , and a i2 , for computing the effective ionization level Az of the NeQuick-G model, are transmitted as part of the Galileo navigation message (EU 2016) and are generally included in the header of RINEX (Receiver INdependent EXchange format; IGS/ RTCM 2019) navigation files collected by the IGS. Given the limited data coverage in early years of the IGS multi-GNSS network (Hoque et al 2019), we made additional use of raw navigation data from the COperative Network for GNSS Observations (CONGO, Montenbruck et al 2011) to retrieve the respective parameters for the year 2014. It may be noted that ionospheric correction parameters may be updated more often than once per day in the Galileo navigation message, but only one randomly chosen set of daily values is typically made available in archived RINEX navigation data files.…”

Section: Data Setsmentioning

confidence: 99%

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NeQuick-G performance assessment for space applications

Montenbruck

Rodríguez

2019

GPS Solut

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Other than traditional single-layer ionosphere models for global navigation satellite system (GNSS) receivers, the NeQuick-G model of Galileo provides a fully three-dimensional description of the electron density and obtains the ionospheric path delay by integration along the line of sight. While optimized for users on or near the surface of the earth, NeQuick-G can thus as well be used for ionospheric correction of single-frequency observations from spaceborne platforms. Based on slant and total electron content measurements obtained in the Swarm mission, the performance of NeQuick-G for users in low earth orbit is assessed for periods of high and low solar activity as well as different orientations of the orbital plane with respect to the sun and the region of high total electron content. A slant range correction performance of better than 70% is achieved in more than 85% of the examined epochs in good accord with the performance reported for terrestrial users. Likewise, the positioning errors can be notably reduced when applying the NeQuick-G corrections in single-frequency navigation solutions. For users at orbital altitudes, it is furthermore shown that vertical total electron predictions from NeQuick-G may be favorably combined with an elevation-dependent thick-layer mapping function to reduce the high computational effort associated with the integration of the electron density along the ray path for each tracked GNSS satellite.

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Section: Slant Tecsupporting

confidence: 85%

Section: Nequick-g Model Description and Leo Applicationmentioning

confidence: 99%

Section: Data Setsmentioning

confidence: 99%

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NeQuick-G performance assessment for space applications

Montenbruck

Rodríguez

2019

GPS Solut

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“…The estimation method employs various physical and empirical models which are describing the daily TEC pattern and mitigating the ionospheric delay in single frequency GNSS receivers [3,16,12]. Because of complex algorithms and powerful computer requirements, physical models are less frequent.…”

Section: (4)mentioning

confidence: 99%

On Global Ionospheric Maps based winter-time GPS ionospheric delay with reference to the Klobuchar model

et al. 2019

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Modelling of the ionospheric Total Electron Content (TEC) represents a challenging and demanding task in Global Navigation Satellite Systems (GNSS) positioning performance. In terms of satellite Positioning, Navigation and Timing (PNT), TEC represents a significant cause of the satellite signal ionospheric delay. There are several approaches to TEC estimation. The Standard (Klobuchar) ionospheric delay correction model is the most common model for Global Positioning System (GPS) single-frequency (L1) receivers. The development of International GNSS Service (IGS) Global Ionospheric Maps (GIM) has enabled the insight into global TEC dynamics. GIM analyses in the Northern Adriatic area have shown that, under specific conditions, local ionospheric delay patterns differ from the one defined in the Klobuchar model. This has been the motivation for the presented research, with the aim to develop a rudimentary model of the TEC estimation, with emphasis on areas where ground truth data are not available. The local pattern of the ionospheric delay has been modelled with wave functions based on the similarity of waveforms, considering diurnal differences in TEC behavior from defined TEC patterns. The model represents a spatiotemporal winter-time ionospheric delay correction with the Klobuchar model as a basis. The evaluation results have shown accurate approximation of the local pattern of the ionospheric delay. The model was verified in the same seasonal period in 2007, revealing it successfulness under pre-defined conditions. The presented approach represents a basis for the further work on the local ionospheric delay modelling, considering local ionospheric and space weather conditions, thus improving the satellite positioning performance for single-frequency GNSS receivers.

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“…A first fusion of IGS-GIMs and ionosondes data from the Global Ionosphere Radio Observatory (GIRO) paves the way for the improvement of real-time International Reference Ionosphere (Froń et al, 2020). Currently, the routine RT-GIMs are available from CAS, CNES, German Aerospace Center in Neutrelitz (DLR-NZ), UPC, WHU, and JPL (Li et al, 2020;Laurichesse and Blot, 2015;Jakowski et al, 2011;Hoque et al, 2019;Roma Dollase et al, 2015;Komjathy et al, 2012). Individual RT-GIMs from different IGS centers can be gathered from IGS-RTS by means of Network Transportation of RTCM by Internet Protocol (NTRIP) (Weber et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

The cooperative IGS RT-GIMs: a global and accurate estimation of the ionospheric electron content distribution in real-time

Liu¹,

Hernández‐Pajares²,

Yang³

et al. 2021

Preprint

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Abstract. The Real-Time Working Group (RTWG) of the International GNSS Service (IGS) is dedicated to providing high-quality data, high-accuracy products for Global Navigation Satellite System (GNSS) positioning, navigation, timing, and Earth observations. As one part of real-time products, the IGS combined Real-Time Global Ionosphere Map (RT-GIM) has been generated by the real-time weighting of the RT-GIMs from IGS real-time ionosphere centers including the Chinese Academy of Sciences (CAS), Centre National d’Etudes Spatiales (CNES), Universitat Politècnica de Catalunya (UPC), and Wuhan University (WHU). The performance of global Vertical Total Electron Content (VTEC) representation in all of the RT-GIMs has been assessed by VTEC from Jason3-altimeter during one month over oceans and dSTEC-GPS technique with 2-day observations over continental regions. According to the Jason3-VTEC and dSTEC-GPS assessment, the real-time weighting technique is sensitive to the accuracy of RT-GIMs. Compared with the performance of post-processed rapid Global Ionosphere Maps (GIMs) and IGS combined final GIM (igsg) during the testing period, the accuracy of UPC RT-GIM (after the transition of interpolation technique) and IGS combined RT-GIM (IRTG) is equivalent to the rapid GIMs and reaches around 2.7 and 3.0 TECU (TEC Unit, 1016 el/m2) over oceans and continental regions, respectively. The accuracy of CAS RT-GIM and CNES RT-GIM is slightly worse than the rapid GIMs, while WHU RT-GIM requires a further upgrade to obtain similar performance. In addition, the strong response to the recent geomagnetic storms has been found in the Global Electron Content (GEC) of IGS RT-GIMs (especially UPC RT-GIM and IGS combined RT-GIM). The IGS RT-GIMs turn out to be reliable sources of real-time global VTEC information and have great potential for real-time applications including range error correction for transionospheric radio signals (such as GNSS positioning, search and rescue, air traffic, radar altimetry, and radioastronomy), the monitoring of space weather (such as geomagnetic and ionospheric storms, ionospheric disturbance) and detection of natural hazards on a global scale (such as hurricanes/typhoons, ionospheric anomalies associated with earthquakes). All the IGS combined RT-GIMs generated and analyzed during the testing period are available at http://doi.org/10.5281/zenodo.4651445 (Liu et al., 2021b).

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Fast ionospheric correction using Galileo Az coefficients and the NTCM model

Cited by 30 publications

References 14 publications

NeQuick-G performance assessment for space applications

NeQuick-G performance assessment for space applications

On Global Ionospheric Maps based winter-time GPS ionospheric delay with reference to the Klobuchar model

The cooperative IGS RT-GIMs: a global and accurate estimation of the ionospheric electron content distribution in real-time

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