A modified mix-differenced approach for estimating multi-GNSS real-time satellite clock offsets

Chen, Yongchang; Yuan, Yunbin; Zhang, Baocheng; Li, Teng; Ding, Wenwu; Ai, Qingsong

doi:10.1007/s10291-018-0739-5

Cited by 15 publications

(9 citation statements)

References 15 publications

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“…where θ j is the satellite elevation at epoch j. The corrections for the Earth rotation, Earth tides, relativistic effects, phase center variation (PCV), and differential code bias (DCB) are implemented [37]. The tropospheric delay was corrected using the Saastamoinen model and the rest wet part was estimated by setting up a piece wise constant (PWC) at an interval of 1 h. The settings for the PPP processing are shown in Table 1.…”

Section: Data and Experimentsmentioning

confidence: 99%

Introduction of the Double-Differenced Ambiguity Resolution into Precise Point Positioning

Xiao

Zhang

et al. 2018

Remote Sensing

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According to the advantages of the precise point positioning (PPP) and the double-differenced (DD) model based algorithm, a new method for the integration of DD integer ambiguity resolution into PPP is presented. This method uses the undifferenced ambiguity estimated with PPP computation and the DD ambiguity generated from the DD model based algorithm to realize the PPP ambiguity fixing. In the presented method, the selection of the undifferenced ambiguity bases on the ratio test of the DD ambiguity and the ratio values based weight is used in PPP processing. This ensures the quality of the used undifferenced ambiguity. To validate the presented method, two experiments are implemented using the ten days (11 to 20 August 2014) data from local and regional reference stations and the moved two receivers. The results of the presented strategy show that improvements are achieved in all three coordinate components. The 1-h, 2-h, and 4-h PPP results indicate that the mean relative improvements were about 19%, 18%, and 15% for north, east, and up components. These results also show that prominent improvements of 29%, 31%, and 25% for north, east, and up components were obtained when the ratio values based weight was used. The application of the presented method in the displacement monitoring was implemented with the experiment and it showed that the PPP estimation computed with the presented strategy benefits local or regional displacement monitoring and improves the detecting ability for displacement.

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Section: Data and Experimentsmentioning

confidence: 99%

Introduction of the Double-Differenced Ambiguity Resolution into Precise Point Positioning

Xiao

Zhang

et al. 2018

Remote Sensing

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show abstract

“…Three primary methods are commonly used in real-time clock estimation, including the undifferenced (UD) method, epoch-differenced (ED) method (Mervart et al 2008;Zhang et al 2011), and mix-differenced (MD) method (Zhang et al 2016;Chen et al 2018). Both ED and MD methods use epoch-differenced carrier phase observations to remove large quantities of ambiguity parameters and speed up the computation.…”

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

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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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“…Multi-GNSS DCB products can be downloaded from International GNSS Service (IGS) data centers, and it is applied to precise positioning and timing applications as a correction. For single point positioning (SPP) based on pseudorange observation and broadcast ephemeris, the satellitedependent code bias can also be corrected using time group delay (TGD) parameters provided by various GNSS, which can be derived from IGS DCB products [14], but this is limited to code-division multiple access (CDMA) systems [15]. Moreover, studies have shown that there are elevation-dependent systematic code-carrier divergences on BDS-2 signal, called BDS satellite-induced code biases, which are likely attributed to the spacecraft internal multipath [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

GNSS Receiver-Related Pseudorange Biases: Characteristics and Effects on Wide-Lane Ambiguity Resolution

Cheng

Wei²,

Liu

et al. 2021

Remote Sensing

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Satellite chip shape distortions lead to signal tracking errors in pseudorange measurements, which are related to the receiver manufacturers, called receiver-related pseudorange biases. Such biases will lead to adverse effects for differential code bias (DCB) and satellite clock estimation, single point positioning (SPP) and precise point positioning (PPP) applications with pseudoranges. In order to assess the characteristics of receiver-related pseudorange biases for global positioning system (GPS), Galileo navigation satellite system (Galileo) and BeiDou navigation satellite system (BDS), seven short baselines from the Multi-GNSS experiment (MGEX) network are tested. The results demonstrate that there are significant inconsistences of pseudorange biases according to satellites, frequencies, receiver and antenna types. For the baselines using the same receivers of TRIMBLE, pseudorange biases are within ±0.2 ns with the same antennas, while they increase to ±0.6 ns with the different antennas. As for baselines with mixed receiver types, pseudorange biases can reach up to 2.5 ns. Among GPS/Galileo/BDS, Galileo shows the smallest pseudorange biases, and the obvious inconsistences of pseudorange biases are observed between BDS-2 and BDS-3, and Galileo in-orbit validation (IOV) satellites and full operational configuration (FOC) satellites. In order to validate receiver-related pseudorange biases, we carry out relative positioning experiments using short baselines. The results show that the RMS values of position errors are reduced 12.6% and 11.4% in horizontal and vertical components with biases correction. The impacts of receiver-related pseudorange biases on wide-lane (WL) ambiguity are also discussed. The results indicate that the percentage of the fractional parts within ±0.1 cycles have an obvious increase with the pseudorange biases correction, and RMS values of the fractional parts are reduced 28.9% and 67.6% for GPS and BDS, respectively.

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A modified mix-differenced approach for estimating multi-GNSS real-time satellite clock offsets

Cited by 15 publications

References 15 publications

Introduction of the Double-Differenced Ambiguity Resolution into Precise Point Positioning

Introduction of the Double-Differenced Ambiguity Resolution into Precise Point Positioning

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

GNSS Receiver-Related Pseudorange Biases: Characteristics and Effects on Wide-Lane Ambiguity Resolution

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