Comparison of Multi-GNSS Time and Frequency Transfer Performance Using Overlap-Frequency Observations

Zhang, Pengfei; Tu, Rui; Gao, Yuping; Hong, Ju; Han, Junqiang; Lu, Xiaochun

doi:10.3390/rs13163130

Cited by 3 publications

(2 citation statements)

References 38 publications

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“…Long-term clock stability limits depend on frequency biases that can vary in time in respond to external or operational parameters acting upon the AFS [32] . Because of its higher frequency stability and lower drift, PHM is more accurate than RAFS [18] , [33] , [34] , [35] , [36] . This higher accuracy makes PHM the perfect tool for testing the fundamental law of physics, which is why H masers were used in space for the first time [37] .…”

Section: Resultsmentioning

confidence: 99%

Gravitational redshift test using Rb clocks of eccentric GPS satellites

Fathollahi¹,

Wu²,

Pongračić³

2023

Heliyon

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Section: Resultsmentioning

confidence: 99%

Gravitational redshift test using Rb clocks of eccentric GPS satellites

Fathollahi¹,

Wu²,

Pongračić³

2023

Heliyon

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“…GNSS is considered an important timing source, which is free, easy to access and highly accurate [ 1 ]. The 2019 Galileo Market report [ 2 ] discusses the use of GNSS timing in critical infrastructures such as telecom, energy and finance.…”

Section: Introductionmentioning

confidence: 99%

Multi-Layer Defences for Robust GNSS Timing Retrieval

Gioia

Borio

2021

Sensors

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A multi-layered interference mitigation approach can significantly improve the performance of Global Navigation Satellite System (GNSS) receivers in the presence of jamming. In this work, three levels of defence are considered including: pre-correlation interference mitigation techniques, post-correlation measurement screening and FDE at the Position, Velocity, and Time (PVT) level. The performance and interaction of these receiver defences are analysed with specific focus on Robust Interference Mitigation (RIM), measurement screening through Lock Indicator (LIs) and Receiver Autonomous Integrity Monitoring (RAIM). The case of timing receivers with a known user position and using Galileo signals from different frequencies has been studied with Time-Receiver Autonomous Integrity Monitoring (T-RAIM) based on the Backward-Forward method. From the experimental analysis it emerges that RIM improves the quality of the measurements reducing the number of exclusions performed by T-RAIM. Effective measurements screening is also fundamental to obtain unbiased timing solutions: in this respect T-RAIM can provide the required level of reliability.

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Performance of Multi-GNSS Real-Time UTC(NTSC) Time and Frequency Transfer Service Using Carrier Phase Observations

Zhang

et al. 2021

Remote Sensing

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The technique of carrier phase (CP), based on the global navigation satellite system (GNSS), has proven to be a highly effective spatial tool in the field of time and frequency transfer with sub-nanosecond accuracy. The rapid development of real-time GNSS satellite orbit and clock determinations has enabled GNSS time and frequency transfer using the CP technique to be performed in real-time mode, without any issues associated with latency. In this contribution, we preliminarily built the prototype system of real-time multi-GNSS time and frequency transfer service in National Time Service Center (NTSC) of the Chinese Academy of Sciences (CAS), which undertakes the task to generate, maintains and transmits the national standard of time and frequency UTC(NTSC). The comprehensive assessment of the availability and quality of the service system were provided. First, we assessed the multi-GNSS state space representation (SSR) correction generated in real-time multi-GNSS prototype system by combining broadcast ephemeris through a comparison with the GeoForschungsZentrum (GFZ) final products. The statistical results showed that the orbit precision in three directions was smaller than 6 cm for global positioning system (GPS) and smaller than approximately 10 cm for BeiDou satellite system (BDS). The root mean square (RMS) values of clock differences for GPS were approximately 2.74 and 6.74 ns for the GEO constellation of BDS, 3.24 ns for IGSO, and 1.39 ns for MEO. The addition, the GLObal NAvigation Satellite System (GLONASS) and Galileo satellite navigation system (Galileo) were 4.34 and 1.32 ns, respectively. In order to assess the performance of real-time multi-GNSS time and frequency transfer in a prototype system, the four real-time time transfer links, which used UTC(NTSC) as the reference, were employed to evaluate the performance by comparing with the solution determined using the GFZ final products. The RMS could reach sub-nanosecond accuracy in the two solutions, either in the SSR or GFZ solution, or in GPS, BDS, GLONASS, and Galileo. The frequency stability within 10,000 s was 3.52 × 10−12 for SSR and 3.47 × 10−12 for GFZ and GPS, 3.63 × 10−12 for SSR and 3.53 × 10−12 for GFZ for BDS, 3.57 × 10−12 for SSR and 3.52 × 10−12 for GFZ for GLONASS, and 3.56 × 10−12 for SSR and 3.48 × 10−12 for GFZ for Galileo.

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Comparison of Multi-GNSS Time and Frequency Transfer Performance Using Overlap-Frequency Observations

Cited by 3 publications

References 38 publications

Gravitational redshift test using Rb clocks of eccentric GPS satellites

Gravitational redshift test using Rb clocks of eccentric GPS satellites

Multi-Layer Defences for Robust GNSS Timing Retrieval

Performance of Multi-GNSS Real-Time UTC(NTSC) Time and Frequency Transfer Service Using Carrier Phase Observations

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