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GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling.

Wang F, Chen X, Guo F - Sensors (Basel) (2015)

Bottom Line: The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling.Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions.However, the refinement of ISB model weakens the correlation between coordinates and ISB estimates and finally enhance the PPP performance in the case of poor observation conditions.

View Article: PubMed Central - PubMed

Affiliation: School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China. fhwang@sgg.whu.edu.cn.

ABSTRACT
Research has demonstrated that receiver clock modeling can reduce the correlation coefficients among the parameters of receiver clock bias, station height and zenith tropospheric delay. This paper introduces the receiver clock modeling to GPS/GLONASS combined precise point positioning (PPP), aiming to better separate the receiver clock bias and station coordinates and therefore improve positioning accuracy. Firstly, the basic mathematic models including the GPS/GLONASS observation equations, stochastic model, and receiver clock model are briefly introduced. Then datasets from several IGS stations equipped with high-stability atomic clocks are used for kinematic PPP tests. To investigate the performance of PPP, including the positioning accuracy and convergence time, a week of (1-7 January 2014) GPS/GLONASS data retrieved from these IGS stations are processed with different schemes. The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling. This is particularly pronounced for the vertical component. Statistic RMSs show that the average improvement of three-dimensional positioning accuracy reaches up to 30%-40%. Sometimes, it even reaches over 60% for specific stations. Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions. In addition to the receiver clock modeling, the impacts of different inter-system timing bias (ISB) models are investigated. For the case of a sufficient number of satellites with fairly good geometry, the PPP performances are not seriously affected by the ISB model due to the low correlation between the ISB and the other parameters. However, the refinement of ISB model weakens the correlation between coordinates and ISB estimates and finally enhance the PPP performance in the case of poor observation conditions.

No MeSH data available.


Related in: MedlinePlus

Positioning errors of kinematic PPP with forward Kalman filter.
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sensors-15-15478-f001: Positioning errors of kinematic PPP with forward Kalman filter.

Mentions: Figure 1 shows that the kinematic positioning results of four IGS tracking stations (namely SVTL, MGUE, HOB2 and WTZR) with the forward Kalman filter (KF). One may notice that Model 1 shows the worst performance, whereas Model 3 shows the best performance. Compared to the GPS-only PPP (Model 1), solutions of the GPS/GLONASS combined PPP (Models 2 and 3) are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites. The improvement can be pronounced particularly in the case of insufficient number of GPS satellites or poor geometry conditions. Solutions of the Model 3 run more stable and smoother than those of the Model 2, especially for the height components. In other words, the positioning accuracy and reliability are improved once the receiver clock modeling algorithm is employed. This is reasonable when we acknowledge the fact that the correlation between the horizontal coordinate and the receiver clock offset is generally small, while the coordinate of the height component is highly correlated with the receiver clock offset. With receiver clock modeling, the process noise can be significantly reduced thus a higher degree of temporal decorrelation of the different parameters can be achieved.


GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling.

Wang F, Chen X, Guo F - Sensors (Basel) (2015)

Positioning errors of kinematic PPP with forward Kalman filter.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541840&req=5

sensors-15-15478-f001: Positioning errors of kinematic PPP with forward Kalman filter.
Mentions: Figure 1 shows that the kinematic positioning results of four IGS tracking stations (namely SVTL, MGUE, HOB2 and WTZR) with the forward Kalman filter (KF). One may notice that Model 1 shows the worst performance, whereas Model 3 shows the best performance. Compared to the GPS-only PPP (Model 1), solutions of the GPS/GLONASS combined PPP (Models 2 and 3) are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites. The improvement can be pronounced particularly in the case of insufficient number of GPS satellites or poor geometry conditions. Solutions of the Model 3 run more stable and smoother than those of the Model 2, especially for the height components. In other words, the positioning accuracy and reliability are improved once the receiver clock modeling algorithm is employed. This is reasonable when we acknowledge the fact that the correlation between the horizontal coordinate and the receiver clock offset is generally small, while the coordinate of the height component is highly correlated with the receiver clock offset. With receiver clock modeling, the process noise can be significantly reduced thus a higher degree of temporal decorrelation of the different parameters can be achieved.

Bottom Line: The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling.Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions.However, the refinement of ISB model weakens the correlation between coordinates and ISB estimates and finally enhance the PPP performance in the case of poor observation conditions.

View Article: PubMed Central - PubMed

Affiliation: School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China. fhwang@sgg.whu.edu.cn.

ABSTRACT
Research has demonstrated that receiver clock modeling can reduce the correlation coefficients among the parameters of receiver clock bias, station height and zenith tropospheric delay. This paper introduces the receiver clock modeling to GPS/GLONASS combined precise point positioning (PPP), aiming to better separate the receiver clock bias and station coordinates and therefore improve positioning accuracy. Firstly, the basic mathematic models including the GPS/GLONASS observation equations, stochastic model, and receiver clock model are briefly introduced. Then datasets from several IGS stations equipped with high-stability atomic clocks are used for kinematic PPP tests. To investigate the performance of PPP, including the positioning accuracy and convergence time, a week of (1-7 January 2014) GPS/GLONASS data retrieved from these IGS stations are processed with different schemes. The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling. This is particularly pronounced for the vertical component. Statistic RMSs show that the average improvement of three-dimensional positioning accuracy reaches up to 30%-40%. Sometimes, it even reaches over 60% for specific stations. Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions. In addition to the receiver clock modeling, the impacts of different inter-system timing bias (ISB) models are investigated. For the case of a sufficient number of satellites with fairly good geometry, the PPP performances are not seriously affected by the ISB model due to the low correlation between the ISB and the other parameters. However, the refinement of ISB model weakens the correlation between coordinates and ISB estimates and finally enhance the PPP performance in the case of poor observation conditions.

No MeSH data available.


Related in: MedlinePlus