Combining GPS, BeiDou, and Galileo Satellite Systems for Time and Frequency Transfer Based on Carrier Phase Observations

Zhang, Pengfei; Tu, Rui; Zhang, Rui; Gao, Yuping; Cai, Hongbin

doi:10.3390/rs10020324

Cited by 58 publications

(30 citation statements)

References 53 publications

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“…As the two external time and frequency references at the ends of one link were real‐time free‐running and varied rapidly during the time transfer experiment, it was difficult to adopt a constant for the performance assessment. In the area of time and frequency transfer, a smooth result is employed to act as a time and frequency criterion [29, 30]. In this study, the Kalman filter for stochastic linear discrete systems was employed to smooth the original clock difference series, and the corresponding root mean square value for the smoothing result was used to assess the noise of time transfer performance.…”

Section: Resultsmentioning

confidence: 99%

Time and frequency transfer using BDS‐2 and BDS‐3 carrier‐phase observations

Zhang

et al. 2019

IET Radar, Sonar & Navigation

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Section: Resultsmentioning

confidence: 99%

Time and frequency transfer using BDS‐2 and BDS‐3 carrier‐phase observations

Zhang

et al. 2019

IET Radar, Sonar & Navigation

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“…The combined observation equation using GPS/BDS/Galileo measurements can therefore be expressed as [ 18 ]:

where the superscripts

, and

represent the GPS, BDS, and Galileo satellite systems, respectively. The subscript

denotes a single satellite.…”

Section: Observation Equation Of Multi-gnss Cp Time Transfermentioning

confidence: 99%

“…This provides the opportunity to combine the three code-division multiple access (CDMA) satellite constellations (i.e., GPS, Galileo and BDS) for precise time and frequency transfer. By increasing the number of available satellites and improving the time dilution of precision, the time transfer solution was determined by combining the three CDMA GNSS constellations, which outperformed single GNSS solutions [ 18 ]. However, the quality of orbit and satellite clock products and pseudo-range observation accuracy of Galileo and BDS differ from those of GPS [ 19 ], and it is therefore inappropriate to treat them equally as has been done in previous studies [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

“…By increasing the number of available satellites and improving the time dilution of precision, the time transfer solution was determined by combining the three CDMA GNSS constellations, which outperformed single GNSS solutions [ 18 ]. However, the quality of orbit and satellite clock products and pseudo-range observation accuracy of Galileo and BDS differ from those of GPS [ 19 ], and it is therefore inappropriate to treat them equally as has been done in previous studies [ 18 ]. Meanwhile, the pseudo-range observation is an important measurement in time and frequency transfers as it carries temporal information [ 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

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Improving the Performance of Multi-GNSS Time and Frequency Transfer Using Robust Helmert Variance Component Estimation

Zhang

Gao

et al. 2018

Sensors

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The combination of multiple Global Navigation Satellite Systems (GNSSs) may improve the performance of time and frequency transfers by increasing the number of available satellites and improving the time dilution of precision. However, the receiver clock estimation is easily affected by the inappropriate weight of multi-GNSSs due to the different characteristics of individual GNSS signals as well as the outliers from observations. Thus, we utilised a robust Helmert variance component estimation (RVCE) approach to determine the appropriate weights of different GNSS observations, and to control for the influence of outliers in these observation in multi-GNSS time and frequency transfer. In order to validate the effectiveness of this approach, four time links were employed. Compared to traditional solutions, the mean improvement of smoothed residuals is 3.43% using the RVCE approach. With respect to the frequency stability of the time links, the RVCE solution outperforms the traditional solution, particularly in the short-term, and the mean improvement is markedly high at 14.89%.

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“…The STD of Galileo-only PPP was improved by 51.4 and 47.6%, respectively, with the troposphere zenith delay constraint and the station coordinates constraint. Moreover, multi-GNSS PPP time transfer was investigated by Zhang et al [14]. The results showed that multi-GNSS time transfer outperformed single GNSS.…”

Section: Introductionmentioning

confidence: 99%

Performance of Multi-GNSS Precise Point Positioning Time and Frequency Transfer with Clock Modeling

Dai

Qin

et al. 2019

Remote Sensing

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Thanks to the international GNSS service (IGS), which has provided multi-GNSS precise products, multi-GNSS precise point positioning (PPP) time and frequency transfer has of great interest in the timing community. Currently, multi-GNSS PPP time transfer is not investigated with different precise products. In addition, the correlation of the receiver clock offsets between adjacent epochs has not been studied in multi-GNSS PPP. In this work, multi-GNSS PPP time and frequency with different precise products is first compared in detail. A receiver clock offset model, considering the correlation of the receiver clock offsets between adjacent epochs using an a priori value, is then employed to improve multi-GNSS PPP time and frequency (scheme2). Our numerical analysis clarify how the approach performs for multi-GNSS PPP time and frequency transfer. Based on two commonly used multi-GNSS products and six GNSS stations, three conclusions are obtained straightforwardly. First, the GPS-only, Galileo-only, and multi-GNSS PPP solutions show similar performances using GBM and COD products, while BDS-only PPP using GBM products is better than that using COD products. Second, multi-GNSS time transfer outperforms single GNSS by increasing the number of available satellites and improving the time dilution of precision. For single-system and multi-GNSS PPP with GBM products, the maximum improvement in root mean square (RMS) values for multi-GNSS solutions are up to 7.4%, 94.0%, and 57.3% compared to GPS-only, BDS-only, and Galileo-only solutions, respectively. For stability, the maximum improvement of multi-GNSS is 20.3%, 84%, and 45.4% compared to GPS-only, BDS-only and Galileo-only solutions. Third, our approach contains less noise compared to the solutions with the white noise model, both for the single-system model and the multi-GNSS model. The RMS values of our approach are improved by 37.8-91.9%, 10.5-65.8%, 2.7-43.1%, and 26.6-86.0% for GPS-only, BDS-only, Galileo-only, and multi-GNSS solutions. For frequency stability, the improvement of scheme2 ranges from 0.2 to 51.6%, from 3 to 80.0%, from 0.2 to 70.8%, and from 0.1 to 51.5% for GPS-only, BDS-only, Galileo-only, and multi-GNSS PPP solutions compared to the solutions with the white noise model in the Eurasia links.

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Combining GPS, BeiDou, and Galileo Satellite Systems for Time and Frequency Transfer Based on Carrier Phase Observations

Cited by 58 publications

References 53 publications

Time and frequency transfer using BDS‐2 and BDS‐3 carrier‐phase observations

Time and frequency transfer using BDS‐2 and BDS‐3 carrier‐phase observations

Improving the Performance of Multi-GNSS Time and Frequency Transfer Using Robust Helmert Variance Component Estimation

Performance of Multi-GNSS Precise Point Positioning Time and Frequency Transfer with Clock Modeling

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