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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

Convergence performances of the kinematic GPS/GLONASS PPP (Model 2 vs. Model 3).
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sensors-15-15478-f005: Convergence performances of the kinematic GPS/GLONASS PPP (Model 2 vs. Model 3).

Mentions: To investigate the benefits of receiver clock modeling for PPP convergence, the same data were reprocessed with the first two hours’ (UTC 0–2) data and reserved only a few valid satellites (approximately three GPS and three GLONASS) to simulate the severe observation environment, which is common in real kinematic sceneries. Figure 5 shows the forward kinematic positioning errors of GPS/GLONASS combined PPP with Model 2 and Model 3. Obviously, the positioning accuracy of the Model 3 is better than that of the Model 2 at the initial stage, thus leading to a shorter convergence time. The positioning accuracy can even be improved by around 0.5 m and 1.0 m in the horizontal and vertical, respectively, for a certain period of time. Moreover, the results of Model 3 are more stable than those of Model 2 after convergence, which indicates that the receiver clock modeling can partly overcome the problem of filter divergence due to the poor geometry. Therefore, the PPP with receiver clock modeling is more capable of enhancing the resistance to terrible observation environments than the conventional PPP.


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

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

Convergence performances of the kinematic GPS/GLONASS PPP (Model 2 vs. Model 3).
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-15478-f005: Convergence performances of the kinematic GPS/GLONASS PPP (Model 2 vs. Model 3).
Mentions: To investigate the benefits of receiver clock modeling for PPP convergence, the same data were reprocessed with the first two hours’ (UTC 0–2) data and reserved only a few valid satellites (approximately three GPS and three GLONASS) to simulate the severe observation environment, which is common in real kinematic sceneries. Figure 5 shows the forward kinematic positioning errors of GPS/GLONASS combined PPP with Model 2 and Model 3. Obviously, the positioning accuracy of the Model 3 is better than that of the Model 2 at the initial stage, thus leading to a shorter convergence time. The positioning accuracy can even be improved by around 0.5 m and 1.0 m in the horizontal and vertical, respectively, for a certain period of time. Moreover, the results of Model 3 are more stable than those of Model 2 after convergence, which indicates that the receiver clock modeling can partly overcome the problem of filter divergence due to the poor geometry. Therefore, the PPP with receiver clock modeling is more capable of enhancing the resistance to terrible observation environments than the conventional PPP.

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