Research on time and frequency transfer during PPP convergence with parameters correlation comparison

Ouyang, Mingjun; Li, Junzhi; Li, Wanqing; Ge, Yulong; Zhu, Xiangwei; Chen, Zhengkun; Dai, Zhiqiang

doi:10.1016/j.measurement.2020.108597

Cited by 6 publications

(7 citation statements)

References 18 publications

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“…More than 80% of independent ambiguities can be consistently addressed, according to experimental findings in the literature [16], and the PPP single-day static solution with fixed ambiguity in the east direction has a positioning accuracy of about 30% greater than the PPP's actual solution. The U direction and the clock difference parameter are correlated, as demonstrated in related research [23], eliminating any remaining uncertainty. This strengthens the position of the U direction and, in turn, the clock difference parameter.…”

Section: Introductionmentioning

confidence: 82%

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Using Various Analysis Center Products to Assess the Time-Frequency Transfer Performance of GPS/Galileo/BDS PPPAR Methods

OuYang¹,

Zhu²,

Yi³

et al. 2022

Preprint

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These days, numerous organizations and Analysis Centers (AC) offer various Ambiguity Resolution (AR) products using various methodologies. To use it for time-frequency transfer, there is no associated study. This paper chooses 16 MGEX stations with external high-precision atomic clocks to constitute 15 international time comparison links and uses AR products data from CNES, SGG, CODE, and PRIDE laboratory, using three ambiguity-fixed strategies, to thoroughly evaluate the effects of various strategies and AR products for high-precision time-frequency transfer. We reach the following results by using the IGS final clock product as a reference and comparing it to ambiguity-float. With various ambiguity-fixed procedures, the time stability STD of time transfer is increased for a single GPS, and the improvement ranges from 10% to 40%. The frequency stability has barely improved; up to 40%, the most notable improvement comes from FCB with GRM products. The time stability STD of combinations has improved after the addition of the Galileo system compared to the single GPS, and the improvement ranges from 2% to 9%. Most strategies have improved, while a few techniques have weakened with the GEC (GPS+Galileo+BDS) combination. We feel that the stability has not significantly increased with the system's increase within short-term stability after comparing multiple groups of linkages.

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Section: Introductionmentioning

confidence: 82%

“…We are aware that there is a strong association between the U direction and clock difference [23]. We assume that the clock difference operates more effectively because the U direction is enhanced.…”

Section: Osb-com Osb-whumentioning

confidence: 99%

Using Various Analysis Center Products to Assess the Time-Frequency Transfer Performance of GPS/Galileo/BDS PPPAR Methods

OuYang¹,

Zhu²,

Yi³

et al. 2022

Preprint

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“…The results show that ionospheric-free (IF)-PPP1 and IF-PPP2 models can be used for precise time transfer using BDS triple-frequency signals, and the accuracy and stability of time transfer are the same in both cases [10]. Verified the improvement of frequency stability during the convergence period when prior information on coordinate was used [11].…”

Section: Introductionmentioning

confidence: 85%

“…Step 4, fixed SD IF ambiguity. After the SD WL and NL are successfully fixed, the SD IF can be recalculated to obtain in equation (11):…”

Section: Gnss Ambiguity-fixed Pppmentioning

confidence: 99%

BDS/QZSS integrated PPPAR time–frequency transfer

Ouyang¹,

Yin²,

Zhu³

et al. 2022

Meas. Sci. Technol.

Self Cite

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Based on BDS, the QZSS system was added to assist in studying the Precise Point Positioning (PPP) time and frequency transfer effect. Ambiguity Resolution (AR) is the key to the rapid conversion of the PPP method. Therefore, this paper also used the Ionospheric-Free (IF) combination and the Observable- Specific Signal Bias (OSB) product of Wuhan University to test the time-frequency transfer effect of BDS ambiguity-fixed. In this way, BDS PPP, BDS+QZSS PPP, BDS PPPAR, and GPS PPP methods were formed. Six stations located in Japan and Australia were selected for experiments. Conclusion: BDS can reach the same level as GPS; When the cut-off angle is greater than 15 degrees, adding QZSS could improve the success rate, accuracy, and frequency stability of the solution of time links effectively; The ambiguity fixed strategy can improve the time transfer accuracy but not the short-term frequency stability.

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“…Furthermore, there are several efforts to enable real-time PPP time transfer. [86][87][88][89][90] The SARAO also has an absolutely calibrated simulator [91][92][93] with specialized antennas and is in the process of setting up a measurement chamber with radio absorbing material to obtain very low and often repeatable measurement and calibration on any time transfer receiver or the optically isolated receiver as mentioned above.…”

Section: Combined Uncertaintymentioning

confidence: 99%

Design, implementation, and qualification of high-performance time and frequency reference for the MeerKAT telescope

Burger

Siebrits

Gamatham

et al. 2022

J. Astron. Telesc. Instrum. Syst.

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The details of the MeerKAT radio telescope's time and frequency reference subsystem that enables sampling via low-jitter, low-drift microwave clock signals, and absolute timing (≤5 ns accurate) are discussed. The subsystem's microwave and pulse per second transmission parts are now fully qualified and commissioned for the ultra high frequency (UHF) and L-bands and also provide for a 100-MHz interface and timing interfaces for S-band receivers that were installed. The subsystem includes a cable measurement system called the Karoo array timing system (KATS). Performance and differences on different bands and seasonal drift of the cable delay measurement of KATS are reported. A time scale called the Karoo Telescope Time (KTT) (which is estimated from tracking a few atomic clocks via new software) and the issuing of timing bulletins to users have been largely implemented and verified. Absolute timing calibration and linkage of KTT to the global positioning system time scale and to different UTC(k) realizations of the Coordinated Universal Time (UTC) instances are described. The subsystem uniquely enables high-fidelity sampling and stable tied array configuration. The latter configuration enables timing and transient science over time spans of 5 to 10 years. Simultaneous subarraying is supported. The backend is unique for radio telescopes in terms of being very deterministic as far as timing is concerned.

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Research on time and frequency transfer during PPP convergence with parameters correlation comparison

Cited by 6 publications

References 18 publications

Using Various Analysis Center Products to Assess the Time-Frequency Transfer Performance of GPS/Galileo/BDS PPPAR Methods

Using Various Analysis Center Products to Assess the Time-Frequency Transfer Performance of GPS/Galileo/BDS PPPAR Methods

BDS/QZSS integrated PPPAR time–frequency transfer

Design, implementation, and qualification of high-performance time and frequency reference for the MeerKAT telescope

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