Evaluation of COMPASS ionospheric model in GNSS positioning

Wu, Xiaoli; Hu, Xiaogong; Wang, Gang; Zhong, Huijuan; Tang, Chengpan

doi:10.1016/j.asr.2012.09.039

Cited by 85 publications

(40 citation statements)

References 9 publications

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“…The derived time series are aligned to a reference satellite in order to remove the system bias, which follows the standard IGS clock comparison procedure [15]. Then the STD values which represent the real-time clock precision are calculated over the seven-day period.…”

Section: Real-time Bds Clock 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: Real-time Bds Clock Resultsmentioning

confidence: 99%

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

et al. 2017

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“…However, the amplitude and period terms in the BDS model are different from those in the GPS model since the geographical reference frame is adopted to estimate BDS BIM parameters. The advantage is that the two axes of the geographic ordinate system are able to reflect daily variation features of the ionosphere, making it easier for model parameterization on daily scale, such as amplitude and period (Wu et al, ).

italicAMP = ({, \begin{array}{l} \sum_{n = 0}^{3} α_{n} {|ϕ_{g}|}^{n}; italicAMP > 0 \\ 0; italicAMP \leq 0 \end{array}),

italicPER = ({, \begin{array}{l} 172, 800; italicPER \geq 172, 800 \\ \sum_{n = 0}^{3} β_{n} {|ϕ_{g}|}^{n}, 172, 800 > italicPER > 72, 000 \\ 72000, italicPER < 72000 \end{array}),

where ϕ g is the geographic latitude of the IPP (in semicircles) with the ionospheric single layer at a height of 375 km; α n and β n ( n = 0, 1, 2, 3) are the eight broadcast coefficients in the BDS navigation message, which are calculated from the regional BDS tracking station data and are updated at a time interval of 2 hr.…”

Section: Methodsmentioning

confidence: 99%

Investigation of Solar Flares Impact on GPS/BDS/GALILEO Broadcast Ionospheric Models

2019

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The ionosphere is significant to solar‐terrestrial space environment, and the ionospheric delay is considered as one main error source in Global Navigation Satellite System (GNSS). For GNSS single‐frequency users, broadcast ionospheric models (BIMs) play an important role in mitigating the ionospheric delay. Solar activity induces ionospheric disturbances, which can reduce the performance of GNSS. In this study, solar flares impact on Global Positioning System/BeiDou satellite navigation System/Galileo (GPS/BDS/GALILEO) BIMs was investigated in the Asia‐Pacific region. Twelve X‐class and M‐class large solar flares were selected for this study. Total electron content (TEC) derived from selected International GNSS Service and Crustal Movement Observation Network of China (CMONOC) were used to analyze the TEC anomalies and the adaptability of the GPS/BDS/GALILEO BIMs during sample solar flare events. It is verified that very noticeable sudden increase in TEC clearly took place during solar flares. The temporal variation of rate of TEC is more pronounced and rapid with respect to that of TEC. Especially, solar flares impact on the correction accuracy of the GPS/BDS/GALILEO BIMs is significant, as illustrated by a noticeable decrease in relative difference between the observed and modeled TEC values of the GPS/BDS/GALILEO BIMs occurred during the events. Through our investigation, we found that the adaptability of BDS BIM is better than GPS and GALILEO BIMs under solar flare conditions because its coefficients were updated more frequently, while the accuracy of the GALILEO BIM is the highest among current GPS/BDS/GALILEO BIMs in general.

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“…During the estimation process of satellite clock offsets, inter-frequency code biases are commonly ignored for reference signals mentioned before, which are assimilated into the satellite clock offsets. When using other signal or combined signals differing from the conventional reference signal or signal combination, the code biases, such as time group delay (TGD) or differential code bias (DCB), should be applied, which are essential for code-based positioning, time service and ionosphere modeling [13]. …”

Section: Introductionmentioning

confidence: 99%

The Impact of Satellite Time Group Delay and Inter-Frequency Differential Code Bias Corrections on Multi-GNSS Combined Positioning

Zhou

Sun

et al. 2017

Sensors

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We present quad-constellation (namely, GPS, GLONASS, BeiDou and Galileo) time group delay (TGD) and differential code bias (DCB) correction models to fully exploit the code observations of all the four global navigation satellite systems (GNSSs) for navigation and positioning. The relationship between TGDs and DCBs for multi-GNSS is clearly figured out, and the equivalence of TGD and DCB correction models combining theory with practice is demonstrated. Meanwhile, the TGD/DCB correction models have been extended to various standard point positioning (SPP) and precise point positioning (PPP) scenarios in a multi-GNSS and multi-frequency context. To evaluate the effectiveness and practicability of broadcast TGDs in the navigation message and DCBs provided by the Multi-GNSS Experiment (MGEX), both single-frequency GNSS ionosphere-corrected SPP and dual-frequency GNSS ionosphere-free SPP/PPP tests are carried out with quad-constellation signals. Furthermore, the author investigates the influence of differential code biases on GNSS positioning estimates. The experiments show that multi-constellation combination SPP performs better after DCB/TGD correction, for example, for GPS-only b1-based SPP, the positioning accuracies can be improved by 25.0%, 30.6% and 26.7%, respectively, in the N, E, and U components, after the differential code biases correction, while GPS/GLONASS/BDS b1-based SPP can be improved by 16.1%, 26.1% and 9.9%. For GPS/BDS/Galileo the 3rd frequency based SPP, the positioning accuracies are improved by 2.0%, 2.0% and 0.4%, respectively, in the N, E, and U components, after Galileo satellites DCB correction. The accuracy of Galileo-only b1-based SPP are improved about 48.6%, 34.7% and 40.6% with DCB correction, respectively, in the N, E, and U components. The estimates of multi-constellation PPP are subject to different degrees of influence. For multi-constellation combination SPP, the accuracy of single-frequency is slightly better than that of dual-frequency combinations. Dual-frequency combinations are more sensitive to the differential code biases, especially for the 2nd and 3rd frequency combination, such as for GPS/BDS SPP, accuracy improvements of 60.9%, 26.5% and 58.8% in the three coordinate components is achieved after DCB parameters correction. For multi-constellation PPP, the convergence time can be reduced significantly with differential code biases correction. And the accuracy of positioning is slightly better with TGD/DCB correction.

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Evaluation of COMPASS ionospheric model in GNSS positioning

Cited by 85 publications

References 9 publications

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

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

Investigation of Solar Flares Impact on GPS/BDS/GALILEO Broadcast Ionospheric Models

The Impact of Satellite Time Group Delay and Inter-Frequency Differential Code Bias Corrections on Multi-GNSS Combined Positioning

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