Improved prediction of GPS satellite clock sub-daily variations based on daily repeat

Strandjord, Kirsten; Axelrad, Penina

doi:10.1007/s10291-018-0723-0

Cited by 15 publications

(6 citation statements)

References 11 publications

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“…Among orbit and clock bias products, the satellite on-board atomic clocks, as one of the main loads, are the references for precise orbit determination and high-accuracy services [5,6]. Currently, considering different accuracy, precision, and time delays, six types of clock bias products are issued by GNSS analysis centers (ACs) of the International GNSS Service (IGS) [7].…”

Section: Introductionmentioning

confidence: 99%

“…According to research studies about satellite clock bias prediction, main points are focused on three contents: the preprocessing strategies for modelling satellites' clock biases [11,12]; analyzing and improving the prediction models [7,8,11,[13][14][15]; and testing and discussing the impact of environments and clock characteristics on modelling satellites' clock biases [16,17]. Furthermore, for algorithms and strategies of clock bias prediction, researchers mainly highlight the investigation of long-term clock products and its optimal solutions, such as the expanded state modelling [18], the introduction of artificial neural network algorithm [19], the combination of multiple periodic terms with trend terms based on an iterative method [13], and the sidereal filtering algorithm including the terms of subdaily clock bias variations [7]. Overall, the widely used clock bias prediction models can be summarized with two types, namely, the polynomial model and the nonlinear model [13,20].…”

Section: Introductionmentioning

confidence: 99%

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Improved Strategies for BeiDou Ultrarapid Satellites’ Clock Bias Prediction Using BDS-2 and BDS-3 Integrated Processing

Wang

2020

Mathematical Problems in Engineering

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GNSS ultrarapid clock biases are key inputs of rapid high-accuracy applications, especially for its prediction parts. With the fast development of the BeiDou system (BDS), the system performances are mainly represented by orbit and clock products. However, it is suggested that the BDS-predicted clock biases cannot meet the requirement of real-time or near real-time services. In this research, the BDS satellite-predicted ultrarapid clock bias products are optimized with three methods, namely, one-step strategy, intersatellite correlation, and variogram model, using the combined estimation of BDS-2 and BDS-3 satellites. Firstly, considering the traditional two-step strategy for modelling clock bias prediction, we take all terms (including trend and periodic terms) into one-step solution of model estimation based on the sparse modelling in machine learning. Secondly, because of the much more stable on-board atomic clock of BDS-3 satellites, the intersatellite correlations between BDS-2 and BDS-3 are utilized to enhance the solution of model coefficients. Thirdly, to further improve the model, the temporal correlations in model residuals are used to reconstruct the stochastic function obtained by variogram. In addition, to verify the proposed improved strategies, 12 schemes of BDS clock bias prediction experiments are designed and analyzed with different conditions. According to the results of predicted clock biases, it is indicted that (1) the stability of BDS-3 on-board clocks is more optimal compared with BDS-2, which can be used to strengthen the solution of the clock bias prediction model; (2) the one-step estimation of the clock bias model by sparse modelling can slightly increase the accuracy of prediction results; (3) both BDS-2- and BDS-3-predicted clock biases benefited each other by inserting the intersatellite correlations into the weight matrix, in which the accuracy of 18-hour period with one-step strategy can be improved by 28.6% and 27.2% for BDS-2 and BDS-3, respectively; and (4) after the introduction of the variogram model in updating the weight matrix, the clock bias prediction model is further corrected by 8.0% and 11.1% for BDS-2 and BDS-3. In summary, improved strategies for BDS ultrarapid satellites’ clock bias prediction using BDS-2 and BDS-3 integrated processing are meaningful for the current BDS ultrarapid satellites’ clock bias prediction products.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved Strategies for BeiDou Ultrarapid Satellites’ Clock Bias Prediction Using BDS-2 and BDS-3 Integrated Processing

Wang

2020

Mathematical Problems in Engineering

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“…(2) refinement of its prediction model [26,27]; (3) analyses of the impact of environmental and physical factors on the clock offset [28]. Moreover, investigations of the algorithms and data processing strategies for the prediction of the clock offset mainly cover improving the estimation and prediction of the clock's long-term behavior, such as investigations of expanded state models [29] and implementation of artificial neural networks [30]; multiple sinusoid approach, including an improved iterative algorithm [31], and sidereal filtering with systematic sub-daily clock bias variations [27].…”

Section: Introductionmentioning

confidence: 99%

A BDS-2/BDS-3 Integrated Method for Ultra-Rapid Orbit Determination with the Aid of Precise Satellite Clock Offsets

Wang

Zhang

2019

Remote Sensing

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The accuracy of ultra-rapid orbits is a key parameter for the performance of GNSS (Global Navigation Satellite System) real-time or near real-time precise positioning applications. The quality of the current BeiDou demonstration system (BDS) ultra-rapid orbits is lower than that of GPS, especially for the new generational BDS-3 satellites due to the fact that the availability of the number of ground tracking stations is limited, the geographic distribution of these stations is poor, and the data processing strategies adopted are not optimal. In this study, improved data processing strategies for the generation of ultra-rapid orbits of BDS-2/BDS-3 satellites are investigated. This includes both observed and predicted parts of the orbit. First, the predicted clock offsets are taken as constraints in the estimation process to reduce the number of the unknown parameters and improve the accuracy of the parameter estimates of the orbit. To obtain more accurate predicted clock offsets for the BDS’ orbit determination, a denoising method (also called the Tikhonov regularization algorithm), inter-satellite correlation, and the partial least squares method are all incorporated into the clock offsets prediction model. Then, the Akaike information criterion (AIC) is used to determine the arc length in the estimation models by taking the optimal arc length in the estimation of the initial orbit states into consideration. Finally, a number of experiments were conducted to evaluate the performance of the ultra-rapid orbits resulting from the proposed methods. Results showed that: (1) Compared with traditional models, the accuracy improvement of the predicted clock offsets from the proposed methods were 40.5% and 26.1% for BDS-2 and BDS-3, respectively; (2) the observed part of the orbits can be improved 9.2% and 5.0% for BDS-2 and BDS-3, respectively, by using the predicted clock offsets as constraints; (3) the accuracy of the predicted part of the orbits showed a high correlation with the AIC value, and the accuracy of the predicted orbits could be improved up to 82.2%. These results suggest that the approaches proposed in this study can significantly enhance the accuracy of the ultra-rapid orbits of BDS-2/BDS-3 satellites.

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“…Diverse methodologies have been studied aiming to improve the clock prediction models as well in the work of Huang (2013), Hauschild and Montenbruck (2008), where a Kalman filter was used to determinate the satellite clock error. More recently, there are studies focused on the clocks' improvements for real time positioning as in the research of Strandjord and Axelrad (2018) where a determination of a sub daily set of the clock parameters is applied.…”

Section: Introductionmentioning

confidence: 99%

Error Behavior of Atomic Clocks Aboard GPS Satellites

Mansur

Ferreira

2019

Bol. Ciênc. Geod.

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The signal transmission and position quality obtained by GNSS positioning directly depends on the time control. The atomic clocks aboard the satellites are responsible for this control. In this research, the satellites clock errors of GPS are studied, using data from the pseudorange, the satellite semi-major axis and the correction parameters of the satellites' clock errors found in the RINEX navigation and observation files. From these data, the satellites' clock errors are calculated using the IGS mathematical model for rubidium and cesium clocks, and then an adjustment technique is applied in order to estimate the new parameters of the clock corrections. For cesium atomic clocks, the periodic part of the mathematical model was adapted. The correction parameters adjusted were applied in the IGS and the adapted model; finally, the results were compared with the IGS data from the clk_30s file. The experiments carried out show an improvement of 50 cm in the cesium satellites' clock errors. In addition, the research concludes that the satellites' clock errors do not depend on the station where the data were collected and the equipment's antenna.

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Improved prediction of GPS satellite clock sub-daily variations based on daily repeat

Cited by 15 publications

References 11 publications

Improved Strategies for BeiDou Ultrarapid Satellites’ Clock Bias Prediction Using BDS-2 and BDS-3 Integrated Processing

Improved Strategies for BeiDou Ultrarapid Satellites’ Clock Bias Prediction Using BDS-2 and BDS-3 Integrated Processing

A BDS-2/BDS-3 Integrated Method for Ultra-Rapid Orbit Determination with the Aid of Precise Satellite Clock Offsets

Error Behavior of Atomic Clocks Aboard GPS Satellites

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