Real-time estimation of multi-GNSS integer recovery clock with undifferenced ambiguity resolution

Li, Xingxing; Xiong, Yun; Yuan, Yongqiang; Wu, Jiaqi; Zhang, Keke; Huang, Jiaxin

doi:10.1007/s00190-019-01312-3

Cited by 20 publications

(6 citation statements)

References 24 publications

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“…In order to eliminate the first-order ionospheric delay, the ionosphere-free (IF) combination is widely used in realtime clock estimation. As for the tropospheric delay, its dry component is usually corrected with an a priori model (Li et al 2019b) In clock estimation, the satellite orbits and station coordinates are held fixed. It should be noted that the satellite clocks are not estimable directly.…”

Section: Undifferenced Model For Multi-gnss Clock Estimationmentioning

confidence: 99%

“…Although ED and MD methods are efficient to realize and can reach comparable accuracy with that of UD method, high computation performance is achieved at the loss of some useful information. The float ambiguity parameters, for example, can be further fixed to get more reliable clock estimation and improve the performance of real-time PPP (Li et al 2019b;Dai et al 2019). As to UD method, satellite clocks are estimated based on undifferenced phase and range observations, and all the useful information is kept.…”

Section: Introductionmentioning

confidence: 99%

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An efficient strategy for multi-GNSS real-time clock estimation based on the undifferenced method

Xiong

et al. 2022

GPS Solut

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Precise satellite clock product is an indispensable prerequisite for the real-time precise positioning service. To meet the requirement of numerous time-critical applications, real-time satellite clock corrections need to be broadcast to users with an update rate of 5 s or higher. With the rapid development of global navigation satellite systems (GNSS) over the past decades, abundant GNSS tracking stations and modern constellations have emerged, and the computation for multi-GNSS real-time clock estimation has become rather time-consuming. In this contribution, an efficient strategy is proposed to achieve high processing efficiency for multi-GNSS real-time clock estimation, wherein undifferenced method based on sequential least square is adopted. In the proposed strategy, parallel data processing and high-performance matrix operations are introduced to accelerate the processing of multi-GNSS clock estimation. The former is based on OpenMP (Open Multi-Processing), while the latter is achieved by the implementation of the Schur complement and the open-source library OpenBLAS. Multi-GNSS observations from 85 globally distributed tracking stations are employed for the generation of real-time precise clock products. The average elapsed time per epoch with the proposed strategy is 0.35, 0.68, and 2.30 s for GPS-only, dual-system, and quad-system solutions, respectively. Compared to the traditional serial strategy, the computation efficiency is significantly improved by 76.0%, 77.3%, and 77.7%, respectively. The accuracy of the estimated clocks is evaluated with respect to IGS final GPS clock products and GFZ final multi-GNSS clock products (GBM0MGXRAP), and multi-GNSS real-time precise point positioning (PPP) experiments are further carried out. All the results indicate that the proposed strategy is efficient, accurate, and can promise high-rate multi-GNSS real-time clock estimation.

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Section: Undifferenced Model For Multi-gnss Clock Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An efficient strategy for multi-GNSS real-time clock estimation based on the undifferenced method

Xiong

et al. 2022

GPS Solut

Self Cite

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“…Thus, users can directly achieve ambiguity resolution by employing WL-FCB and IRC product. Furthermore, the IRC method has also been extended to multi-system PPP-AR, as demonstrated by Li et al [10]. Following this, a decoupling clock method was introduced by Collins et al [11], which utilized both code and phase observations to estimate the code clock offset and phase clock offset separately.…”

Section: Introductionmentioning

confidence: 99%

Validation and assessment of multi-GNSS phase bias products from IGS analysis centers

Lyu,

Wang,

et al. 2024

Meas. Sci. Technol.

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Phase bias plays a crucial role in Precision Point Positioning (PPP) with ambiguity resolution. Currently, an increasing number of analysis centers are being of releasing multi-GNSS phase bias products. However, it remains uncertain how different phase bias products, receiver types, and GNSS systems combinations might impact user-side positioning performance and ambiguity resolution capabilities. In view of this, this contribution systematically investigates the effects on PPP with ambiguity resolution. Four types of receivers, including SEPT POLARX5, LEICA GR50, JAVAD TRE_3 DELTA, and TRIMBLE ALLOY, are selected, and six types of GNSS system combinations, namely, GPS, Galileo, BDS3, GPS/Galileo, GPS/BDS3, GPS/Galileo/BDS3, are used, and the phase bias products from OSB-CODE, OSB-CNES/CLS, OSB-GFZ, OSB-WHU, OSB-CNES/NAV, IRC-CNES/CLS, IRC-GFZ are adopted for the numerical experiment. Compared with the float-solution, the results show that the accuracy of PPP fixed-solution with single-system can be improved 1cm~3cm, and the convergence time is reduced 2min~ 15min. The positioning performance using the seven phase bias products for any single-system satisfies the following order from the best to the worst: OSB_WHU > OSB_CODE > OSB_CNES/CLS ≈ OSB_CNES/NAV > OSB_GFZ > IRC_CNES/CLS ≈ IRC_GFZ, but the performance of ambiguity resolution do not present certain characteristics. Meanwhile, the ambiguity-fix success-rate and TTFF can keep at 80%~96% and 20min~40min with single-system, respectively. In the case of multi-system, although the difference in the positioning performance among the phase bias products is not significant, the multi-system outperforms the single-systemin terms of both positioning performance and ambiguity resolution. However, the difference between the dual-system and the triple-system is smaller. In addition, the positioning performance corresponding to different receiver types also shows distinction, while there is no significant difference in the ambiguity resolution performance between different receiver types.

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“…The BDS-3 new signals have been used in diverse precise data processing applications. Although the AR technology can improve the estimated satellite clock offset performance [18], the legacy B1I/B3I signals were used in previous studies. Considering that the signal frequency, structure, modulation techniques, and bandwidth are different for the B1I/B3I and B1C/B2a combination, we evaluated and compared the performance of BDS-3 ambiguity-fixed real-time satellite clock offset between the legacy B1I/B3I and new B1C/B2a signals.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Estimation of BDS-3 Satellite Clock Offset with Ambiguity Resolution Using B1C/B2a Signals

Xie,

Wang,

et al. 2024

Remote Sensing

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The third generation of the BeiDou navigation satellite system (BDS-3) can transmit five-frequency signals. The real-time satellite clock offset of BDS-3 is typically generated utilizing the B1I/B3I combination with the ambiguity-float solutions. By conducting the ambiguity resolution (AR), the reliability of the satellite clock offset can be improved. However, the performance of BDS-3 ambiguity-fixed real-time satellite clock offset with B1C/B2a signals remains unknown and unrevealed. In this contribution, the performance of the BDS-3 ambiguity-fixed satellite clock offset with the new B1C/B2a signals is investigated. One week of observation data from 85 stations was used to perform ambiguity-fixed satellite clock offset estimation. For B1I/B3I and B1C/B2a signals, the wide-lane (WL) uncalibrated phase delay (UPD) on the satellite end is fairly stable for one day, while the narrow-lane (NL) UPD standard deviation (STD) amounts to 0.122 and 0.081 cycles, respectively. The mean ambiguity fixing rate is 80.7% and 78.0% for these two signal combinations, and the time to first fix (TTFF) for the B1C/B2a signals is remarkably shorter than that of the B1I/B3I signals. The STDs of the ambiguity-float and -fixed satellite clock offsets are 0.033 and 0.026 ns, respectively, for the B1I/B3I combination, and it is reduced to 0.024 and 0.023 ns for B1C/B2a signals, respectively. Using the estimated UPD and clock offset products, the positioning performance of the kinematic Precise Point Positioning (PPP)-AR results amounts to 1.56, 1.23, and 4.46 cm in the east, north, and up directions for B1I/B3I signals, respectively. It is improved to 1.36, 1.16, and 4.25 cm using the products estimated with the B1C/B2a signals, with improvements of 12.8%, 5.7%, and 4.7% in three directions, respectively. The experiments showed that the performances of the ambiguity-fixed satellite clock offsets and the PPP-AR results using B1C/B2a signals are better than those of B1I/B3I.

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Real-time estimation of multi-GNSS integer recovery clock with undifferenced ambiguity resolution

Cited by 20 publications

References 24 publications

An efficient strategy for multi-GNSS real-time clock estimation based on the undifferenced method

An efficient strategy for multi-GNSS real-time clock estimation based on the undifferenced method

Validation and assessment of multi-GNSS phase bias products from IGS analysis centers

Real-Time Estimation of BDS-3 Satellite Clock Offset with Ambiguity Resolution Using B1C/B2a Signals

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