Geopotential determination based on a direct clock comparison using two-way satellite time and frequency transfer

According to general relativity theory, one may determine the geopotential difference between two arbitrary stations by comparing there-located clocks&#8217; running rates. In this study, we provide experimental results of the geopotential determination based on the time elapse comparison between two hydrogen atomic clocks, one fixed clock &#160;and one portable clock , using the common view satellite time transfer (CVSTT) technique. We compared the portable clock &#160;located at Jiugongshan Time Frequency Station (JTFS) with the fixed clock &#160;located at Luojiashan Time Frequency Station (LTFS) for 30 days. The two stations are separated by a geographic distance of around 240 km with height difference around 1230 m. Then the clock &#160;was transported (without stopping its running status) to LTFS and compared with clock &#160;for zero-baseline calibration for 15 days. The clock-comparison-determined geopotential difference between JTFS and LTFS is determined. Results show that the clock-comparison-determined result deviates from the EGM20080-determined result by about 2322&#177;1609 m2s-2, equivalent to 237&#177;164 &#160;m in height, in consistence with the stability of the hydrogen atomic clocks applied in the experiments (at the level of 10-15/day).This study is supported by NSFCs (grant Nos. 41721003, 41631072, 41874023, 41804012, 41429401, 41574007) and Natural Science Foundation of Hubei Province of China (grant No. 2019CFB611).

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Experiments of determining the geopotential difference using two hydrogen atomic clocks and two-way satellite time and frequency transfer technique

10.5194/egusphere-egu2020-3388 ◽

2020 ◽

Author(s):

An Ning ◽

Kuangchao Wu ◽

Wen-Bin Shen ◽

Ziyu Shen ◽

Chenghui Cai ◽

...

Keyword(s):

Ensemble Empirical Mode Decomposition ◽

Conventional Approach ◽

Atomic Clocks ◽

Mode Decomposition ◽

Height System ◽

Empirical Mode Decomposition Method ◽

Clock Comparison ◽

The Stability ◽

Geopotential Determination ◽

Vertical Height

Abstract In this study, we carried out experiments of the geopotential difference determination at CASIC, Beijing with the help of two hydrogen atomic clocks, using the two-way satellite time and frequency transfe technique. Here the ensemble empirical mode decomposition method is adopted to extract geopotential-related time-elapse signals from the original observations. The clock-comparison-determined geopotential difference in the experiments is determined, which is compared to the previously known results determined by conventional approach. Results show that the geopotential difference determined by time comparison deviates from that determined by conventional approach by about 1589 m2s-2, which is equivalent to 162 m in height, in consistence with the stability of the hydrogen atomic clocks applied in the experiments (at the level of 10-15/day). Since the stability of the optical clocks achieve 10-18 level, the geopotential determination by accurate clocks is prospective, and it is prospective to realize the unification of the world vertical height system. This study is supported by NSFCs (grant Nos. 41721003, 41631072, 41874023, 41804012, 41429401, 41574007) and Natural Science Foundation of Hubei Province of China (grant No. 2019CFB611).

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Propagation Time Correction on Earth's Orbital Motion for Two-way Satellite Time and Frequency Transfer

Proceedings of the ION 2017 Pacific PNT Meeting ◽

10.33012/2017.15056 ◽

2017 ◽

Cited By ~ 1

Author(s):

Wen-Hung Tseng

Keyword(s):

Orbital Motion ◽

Propagation Time ◽

Time Correction ◽

Frequency Transfer

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Precise frequency transfer model suitable for short baseline link based on GPS single-differenced observations with ambiguity resolution

Acta Geodaetica et Geophysica ◽

10.1007/s40328-021-00332-w ◽

2021 ◽

Author(s):

Rui Tu ◽

Pengfei Zhang ◽

Rui Zhang ◽

Lihong Fan ◽

Junqiang Han ◽

...

Keyword(s):

Ambiguity Resolution ◽

Transfer Model ◽

Short Baseline ◽

Frequency Transfer

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Modeling and Analysis of BDS-2 and BDS-3 Combined Precise Time and Frequency Transfer Considering Stochastic Models of Inter-System Bias

Remote Sensing ◽

10.3390/rs13040793 ◽

2021 ◽

Vol 13 (4) ◽

pp. 793

Author(s):

Guoqiang Jiao ◽

Shuli Song ◽

Qinming Chen ◽

Chao Huang ◽

Ke Su ◽

...

Keyword(s):

Stochastic Models ◽

Satellite System ◽

Modeling And Analysis ◽

System Bias ◽

Frequency Transfer ◽

Global Navigation ◽

The Difference ◽

The Stability ◽

Global Navigation Satellite ◽

Precise Time

BeiDou global navigation satellite system (BDS) began to provide positioning, navigation, and timing (PNT) services to global users officially on 31 July, 2020. BDS constellations consist of regional (BDS-2) and global navigation satellites (BDS-3). Due to the difference of modulations and characteristics for the BDS-2 and BDS-3 default civil service signals (B1I/B3I) and the increase of new signals (B1C/B2a) for BDS-3, a systemically bias exists in the receiver-end when receiving and processing BDS-2 and BDS-3 signals, which leads to the inter-system bias (ISB) between BDS-2 and BDS-3 on the receiver side. To fully utilize BDS, the BDS-2 and BDS-3 combined precise time and frequency transfer are investigated considering the effect of the ISB. Four kinds of ISB stochastic models are presented, which are ignoring ISB (ISBNO), estimating ISB as random constant (ISBCV), random walk process (ISBRW), and white noise process (ISBWN). The results demonstrate that the datum of receiver clock offsets can be unified and the ISB deduced datum confusion can be avoided by estimating the ISB. The ISBCV and ISBRW models are superior to ISBWN. For the BDS-2 and BDS-3 combined precise time and frequency transfer using ISBNO, ISBCV, ISBRW, and ISBWN, the stability of clock differences of old signals can be enhanced by 20.18%, 23.89%, 23.96%, and 11.46% over BDS-2-only, respectively. For new signals, the enhancements are −50.77%, 20.22%, 17.53%, and −3.69%, respectively. Moreover, ISBCV and ISBRW models have the better frequency transfer stability. Consequently, we recommended the optimal ISBCV or suboptimal ISBRW model for BDS-2 and BDS-3 combined precise time and frequency transfer when processing the old as well as the new signals.

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Time and frequency transfer by geodetic GPS: Comparison of receivers and computation techniques

2009 IEEE International Frequency Control Symposium Joint with the 22nd European Frequency and Time forum ◽

10.1109/freq.2009.5168183 ◽

2009 ◽

Author(s):

Gerard Petit ◽

Laurent-Guy Bernier ◽

Pierre Uhrich

Keyword(s):

Computation Techniques ◽

Frequency Transfer

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Portable Atmospheric Frequency Transfer over Outdoor Free-space Link with Compact Diode Laser

2020 IEEE 20th International Conference on Communication Technology (ICCT) ◽

10.1109/icct50939.2020.9295691 ◽

2020 ◽

Author(s):

Jie Tian ◽

Zhengyu Ji ◽

Dong Hou

Keyword(s):

Diode Laser ◽

Free Space ◽

Frequency Transfer

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Modeling and Performance Evaluation of Precise Positioning and Time-Frequency Transfer with Galileo Five-Frequency Observations

Remote Sensing ◽

10.3390/rs13152972 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2972

Author(s):

Wei Xu ◽

Wen-Bin Shen ◽

Cheng-Hui Cai ◽

Li-Hong Li ◽

Lei Wang ◽

...

Keyword(s):

Three Dimensional ◽

Satellite Orbit ◽

Average Frequency ◽

Satellite System ◽

Observation Data ◽

Navigation Satellite ◽

Dual Frequency ◽

Time Frequency ◽

Combination Model ◽

Frequency Transfer

The present Global Navigation Satellite System (GNSS) can provide at least double-frequency observations, and especially the Galileo Navigation Satellite System (Galileo) can provide five-frequency observations for all constellation satellites. In this contribution, precision point positioning (PPP) models with Galileo E1, E5a, E5b, E5 and E6 frequency observations are established, including a dual-frequency (DF) ionospheric-free (IF) combination model, triple-frequency (TF) IF combination model, quad-frequency (QF) IF combination model, four five-frequency (FF) IF com-bination models and an FF uncombined (UC) model. The observation data of five stations for seven days are selected from the multi-GNSS experiment (MGEX) network, forming four time-frequency links ranging from 454.6 km to 5991.2 km. The positioning and time-frequency transfer performances of Galileo multi-frequency PPP are compared and evaluated using GBM (which denotes precise satellite orbit and clock bias products provided by Geo Forschung Zentrum (GFZ)), WUM (which denotes precise satellite orbit and clock bias products provided by Wuhan University (WHU)) and GRG (which denotes precise satellite orbit and clock bias products provided by the Centre National d’Etudes Spatiales (CNES)) precise products. The results show that the performances of the DF, TF, QF and FF PPP models are basically the same, the frequency stabilities of most links can reach sub10−16 level at 120,000 s, and the average three-dimensional (3D) root mean square (RMS) of position and average frequency stability (120,000 s) can reach 1.82 cm and 1.18 × 10−15, respectively. The differences of 3D RMS among all models are within 0.17 cm, and the differences in frequency stabilities (in 120,000 s) among all models are within 0.08 × 10−15. Using the GRG precise product, the solution performance is slightly better than that of the GBM or WUM precise product, the average 3D RMS values obtained using the WUM and GRG precise products are 1.85 cm and 1.77 cm, respectively, and the average frequency stabilities at 120,000 s can reach 1.13 × 10−15 and 1.06 × 10−15, respectively.

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