scholarly journals Research of Eliminating the Day-Boundary Discontinuities in GNSS Carrier Phase Time Transfer through Network Processing

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2622
Author(s):  
Xiangbo Zhang ◽  
Ji Guo ◽  
Yonghui Hu ◽  
Dangli Zhao ◽  
Zaimin He
Keyword(s):  
Carrier Phase ◽  
Satellite System ◽  
Least Square ◽  
Observation Data ◽  
Time Transfer ◽  
International Gnss Service ◽  
Phase Time ◽  
Clock Stability ◽  
Network Processing

Time and frequency transfer through global navigation satellite system (GNSS) precise point positioning (PPP) based on carrier-phase measurements has been widely used for clock comparisons in national timing laboratories. However, the time jumps up to one nanosecond at the day boundary epochs of adjacent daily batches lead to discontinuities in the time transfer results. Therefore, it is a major obstacle to achieve continuous carrier phase time transfer. The day-boundary discontinuities have been studied for many years, and they are believed to be caused by the long-term pseudorange noise during estimation of the clock offset in the daily batches and are nearly in accordance with a Gaussian curve. Several methods of eliminating the day-boundary discontinuity were proposed during the past fifteen years, such as shift and overlapping, longer batch processing, clock handover, and ambiguity stacking. Some errors and new noise limit the use of such methods in the long-term clock stability comparison. One of the effective methods is phase ambiguity fixing resolution in zero-differenced PPP, which is based on the precise products of wide-lane satellite bias (WSB) provided by the new international GNSS Service (IGS) Analysis Center of Centre National d’Etudes Spatiales (CNES) and Collecte Localisation Satellites (CLS). However, it is not suitable for new GNSS, such as the Beidou Satellite System (BDS), GALILEO, and QZSS. For overcoming the drawbacks above, Multi-GNSS Experiment (MGEX) observation data of 10 whole days from MJD 58624 to 58633have been network processed by batch least square resolution. These observations come from several ground receivers located in different national timing laboratories. Code and carrier phase ionosphere-free measurements of GPS and BDS satellites are used, and the time transfer results from network processing are compared with PPP results provided by Bureau International des Poids et Mesures (BIPM) and used for international atomic time (TAI) computation (TAIPPP) and universal time coordination (UTC). It is shown that the time offsets of three different time links are almost continuous and the day-boundary discontinuities are sharply eliminated by network processing, although a little extent of day-boundary discontinuities still exist in the results of UTC(USNO)-UTC(PTB). The accuracy of time transfer has been significantly improved, and the frequency stability of UTC(NTSC)-UTC(PTB) can be up to 6.8 × 10−15 on average time of more than one day. Thus, it is suitable for continuous multi-GNSS time transfer, especially for long-term clock stability comparison.

scholarly journals Consideration of GLONASS Inter-Frequency Code Biases in Precise Point Positioning (PPP) International Time Transfer

2018 ◽  
Vol 8 (8) ◽  
pp. 1254 ◽  
Author(s):  
Yulong Ge ◽  
WeiJin Qin ◽  
Xinyun Cao ◽  
Feng Zhou ◽  
Shengli Wang ◽  
...  
Keyword(s):  
Precise Point Positioning ◽  
Satellite Observation ◽  
Satellite System ◽  
Observation Data ◽  
Time Transfer ◽  
International Gnss Service ◽  
Frequency Code ◽  
Glonass Satellite ◽  
Point Positioning ◽  
Global Navigation Satellite

International time transfer based on Global Navigation Satellite System (GLONASS) precise point positioning (PPP) is influenced by inter-frequency code biases (IFCBs) because of the application of frequency division multiple access technique. This work seeks to gain insight into the influence of GLONASS IFCBs on international time transfer based on GLONASS-only PPP. With a re-parameterization process, three IFCB handling schemes are proposed: neglecting IFCBs, estimating IFCB for each GLONASS frequency number, and estimating IFCB for each GLONASS satellite. Observation data collected from 39 globally distributed stations in a 71-day period (DOY 227–297, 2017) was exclusively processed. For the comparison reason, Global Positioning System (GPS)-only PPP solutions were regarded as reference values. The clock differences derived from GPS- and GLONASS-only PPP solutions were then analyzed. The experimental results demonstrated that considering GLONASS IFCBs could reduce standard deviation (STD) of the clock differences for both identical receiver types and mixed receiver types, of which reduction was from 3.3% to 62.6%. Furthermore, compared with neglecting IFCBs, STD of the clock differences with estimating IFCB for each GLONASS satellite in coordinate-fixed mode was reduced by more than 30% from 0.30 to 0.20 ns, and by 10% from 0.40 to 0.35 ns, for 1-day arc solutions and 10-day arc solutions, respectively. Moreover, different precise products from three International GNSS Service (IGS) analysis centers were also evaluated. Even though different IFCB handling schemes were adopted in GLONASS satellite clock estimation, our numerical results showed that international time transfer on the basis of estimating IFCB for each GLONASS satellite better than the other two processing schemes. To achieve high-precision GLONASS-only PPP-based international time transfer, it is highly recommended to estimate IFCB for each GLONASS satellite.

scholarly journals The research on carrier phase time transfer method based on least curve fitting

2021 ◽  
Vol 783 (1) ◽  
pp. 012091
Author(s):  
Xiang-Lei Wang ◽  
Shi-Yi Xu ◽  
Jing-Xuan Xu ◽  
Fei Zeng
Keyword(s):  
Curve Fitting ◽  
Carrier Phase ◽  
Time Transfer ◽  
Phase Time ◽  
Transfer Method

A detailed comparison of two continuous GPS carrier-phase time transfer techniques

Metrologia ◽  
2015 ◽  
Vol 52 (5) ◽  
pp. 666-676 ◽  
Author(s):  
Jian Yao ◽  
Ivan Skakun ◽  
Zhiheng Jiang ◽  
Judah Levine
Keyword(s):  
Carrier Phase ◽  
Detailed Comparison ◽  
Time Transfer ◽  
Phase Time ◽  
Continuous Gps

The analysis on BDS-3 carrier phase time transfer under the mode of basic navigation Mode

2021 ◽  
Author(s):  
Weijin Qin ◽  
Hang Su ◽  
Pei Wei ◽  
Haiyan Yang ◽  
Xiao Li ◽  
...  
Keyword(s):  
Carrier Phase ◽  
Time Transfer ◽  
Phase Time ◽  
Navigation Mode

scholarly journals Improved Ultra-Rapid UT1-UTC Determination and Its Preliminary Impact on GNSS Satellite Ultra-Rapid Orbit Determination

2020 ◽  
Vol 12 (21) ◽  
pp. 3584
Author(s):  
Fei Ye ◽  
Yunbin Yuan ◽  
Zhiguo Deng
Keyword(s):  
Piecewise Linear ◽  
Satellite System ◽  
Assessment System ◽  
Least Square ◽  
Linear Functions ◽  
Observation Data ◽  
Combination Model ◽  
New Strategy ◽  
Global Navigation Satellite ◽  
Traditional Strategy

Errors in ultra-rapid UT1-UTC primarily affect the overall rotation of spatial datum expressed by GNSS (Global Navigation Satellite System) satellite ultra-rapid orbit. In terms of existing errors of traditional strategy, e.g., piecewise linear functions, for ultra-rapid UT1-UTC determination, and the requirement to improve the accuracy and consistency of ultra-rapid UT1-UTC, the potential to improve the performance of ultra-rapid UT1-UTC determination based on an LS (Least Square) + AR (Autoregressive) combination model is explored. In this contribution, based on the LS+AR combination model and by making joint post-processing/rapid UT1-UTC observation data, we propose a new strategy for ultra-rapid UT1-UTC determination. The performance of the new strategy is subsequently evaluated using data provided by IGS (International GNSS Services), iGMAS (international GNSS Monitoring and Assessment System), and IERS (International Earth Rotation and Reference Systems Service). Compared to the traditional strategy, the numerical results over more than 1 month show that the new strategy improved ultra-rapid UT1-UTC determination by 29–43%. The new strategy can provide a reference for GNSS data processing to improve the performance of ultra-rapid products.

An Improved Geometry-free Three Carrier Ambiguity Resolution Method for the BeiDou Navigation Satellite System

2016 ◽  
Vol 69 (6) ◽  
pp. 1393-1408 ◽  
Author(s):  
Xing Wang ◽  
Wenxiang Liu ◽  
Guangfu Sun
Keyword(s):  
Ambiguity Resolution ◽  
Carrier Phase ◽  
Success Probability ◽  
Satellite System ◽  
Observation Data ◽  
Short Baseline ◽  
Long Baseline ◽  
Triple Frequency ◽  
Wide Lane ◽  
Three Carrier Ambiguity Resolution

BeiDou satellites transmit triple-frequency signals, which bring substantial benefits to carrier phase Ambiguity Resolution (AR). The traditional geometry-free model Three-Carrier Ambiguity Resolution (TCAR) method looks for a suitable combination of carrier phase and code-range observables by searching and comparing in the integer range, which limits the AR success probability. By analysing the error characteristics of the BeiDou triple-frequency observables, we introduce a new procedure to select the optimal combination of carrier phase and code observables to resolve the resolution of Extra-Wide-Lane (EWL) and Wide-Lane (WL) ambiguity. We also investigate a geometry-free and ionosphere-eliminated method for AR of the Medium-Lane (ML) and Narrow-Lane (NL) observables. In order to evaluate the performance of the improved TCAR method, real BeiDou triple-frequency observation data for different baseline cases were collected and processed epoch-by-epoch. The results show that the improved geometry-free TCAR method increases the single epoch AR success probability by up to 90% for short baseline and 80% for long baseline. The A perfect (100%) AR success probability can also be effortlessly achieved by averaging the float ambiguities over just tens of epochs.

GPS carrier phase time transfer using a modified solution model

2012 ◽  
Author(s):  
Liang Kun ◽  
Li Tianchu ◽  
Wang Weibo ◽  
Ning Dayu ◽  
Zhang Aimin ◽  
...  
Keyword(s):  
Carrier Phase ◽  
Solution Model ◽  
Time Transfer ◽  
Phase Time
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