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

2019 ◽  
Vol 11 (3) ◽  
pp. 347 ◽  
Author(s):  
Yulong Ge ◽  
Peipei Dai ◽  
Weijin Qin ◽  
Xuhai Yang ◽  
Feng Zhou ◽  
...  
Keyword(s):  
White Noise ◽  
Precise Point Positioning ◽  
Noise Model ◽  
Single System ◽  
Time Transfer ◽  
Receiver Clock ◽  
Maximum Improvement ◽  
Frequency Transfer ◽  
White Noise Model ◽  
Point Positioning

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.

Enhancing real-time precise point positioning time and frequency transfer with receiver clock modeling

GPS Solutions ◽  
2018 ◽  
Vol 23 (1) ◽  
Author(s):  
Yulong Ge ◽  
Feng Zhou ◽  
Tianjun Liu ◽  
WeiJin Qin ◽  
Shengli Wang ◽  
...  
Keyword(s):  
Real Time ◽  
Precise Point Positioning ◽  
Receiver Clock ◽  
Frequency Transfer ◽  
Point Positioning ◽  
Positioning Time

scholarly journals BDS-3/Galileo Time and Frequency Transfer with Quad-Frequency Precise Point Positioning

2021 ◽  
Vol 13 (14) ◽  
pp. 2704
Author(s):  
Yulong Ge ◽  
Xinyun Cao ◽  
Fei Shen ◽  
Xuhai Yang ◽  
Shengli Wang
Keyword(s):  
Mathematical Models ◽  
Precise Point Positioning ◽  
Tropospheric Delay ◽  
Dual Frequency ◽  
Time Transfer ◽  
Positioning Accuracy ◽  
Frequency Transfer ◽  
Point Positioning ◽  
Transfer Method ◽  
Stability And Accuracy

In this work, quad-frequency precise point positioning (PPP) time and frequency transfer methods using Galileo E1/E5a/E5b/E5 and BDS-3 B1I/B3I/B1C/B2a observations were proposed with corresponding mathematical models. In addition, the traditional dual-frequency (BDS-3 B1I/B3I and Galileo E1/E5a) ionospheric-free (IF) model was also described and tested for comparison. To assess the proposed method for time transfer, datasets selected from timing labs were utilized and tested. Moreover, the number of Galileo or BDS-3 satellites, pseudorange residuals, positioning accuracy and tropospheric delay at receiver end were all analyzed. The results showed that the proposed quad-frequency BDS-3 or Galileo PPP models could be used to time transfer, due to stability and accuracy identical to that of dual-frequency IF model. Furthermore, the quad-frequency models can provide potential for enhancing the reliability and redundancy compared to the dual-frequency time transfer method.

scholarly journals Precise Point Positioning for TAI Computation

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Gérard Petit ◽  
Zhiheng Jiang
Keyword(s):  
Time Scale ◽  
Carrier Phase ◽  
Precise Point Positioning ◽  
Dual Frequency ◽  
Time Transfer ◽  
Short Term ◽  
Reference Time ◽  
Local Clock ◽  
Point Positioning ◽  
Simple Difference

We discuss the use of some new time transfer techniques for computing TAI time links. Precise point positioning (PPP) uses GPS dual frequency carrier phase and code measurements to compute the link between a local clock and a reference time scale with the precision of the carrier phase and the accuracy of the code. The time link between any two stations can then be computed by a simple difference. We show that this technique is well adapted and has better short-term stability than other techniques used in TAI. We present a method of combining PPP and two-way time transfer that takes advantage of the qualities of each technique, and shows that it would bring significant improvement to TAI links.

scholarly journals Empirical Bayes scaling of Gaussian priors in the white noise model

2013 ◽  
Vol 7 (0) ◽  
pp. 991-1018 ◽  
Author(s):  
B. T. Szabó ◽  
A. W. van der Vaart ◽  
J. H. van Zanten
Keyword(s):  
White Noise ◽  
Empirical Bayes ◽  
Noise Model ◽  
White Noise Model

Experimental study on effect of side-mooring lines on dynamics of a catenary moored semi-submersible system

2019 ◽  
Vol 234 (1) ◽  
pp. 127-142
Author(s):  
Sheng Xu ◽  
Chun-yan Ji ◽  
C Guedes Soares
Keyword(s):  
White Noise ◽  
Model Tests ◽  
Noise Model ◽  
Floating Platform ◽  
Mooring Lines ◽  
Motion Response ◽  
Free Decay ◽  
Wave Basin ◽  
White Noise Model ◽  
Response Amplitude Operators

In this article, a novel mooring system with side-mooring lines is proposed for a traditional shape semi-submersible platform with four columns. To obtain the dynamics of moored system, model tests were carried out at a wave basin, including free-decay model tests, white noise model tests and irregular model tests. The natural periods in heave, roll and pitch models were measured and compared with numerical results. The motion response amplitude operators under 90° and 135° waves were obtained from white noise model tests and then compared with numerical simulations. A 100-year sea state in South China Sea was simulated in the wave basin by the JONSWAP spectrum, and the 6-degree-of-freedom motion responses of semi-submersible and mooring tensions were recorded in beam and quartering seas. The effects of the side-mooring lines on the floating platform motion response, mooring tensions and mooring fatigue damage are evaluated by comparing the results with and without side-mooring lines installed.

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