Study of time link calibration based on GPS carrier phase observation

Zhang, Pengfei; Tu, Rui; Gao, Yuping; Guang, Wang; Zhang, Rui; Cai, Hongbin

doi:10.1049/iet-rsn.2018.5096

Cited by 8 publications

(7 citation statements)

References 14 publications

(20 reference statements)

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“…Both the SF model and DF model for time transfer, the unknown parameter of receiver clock offset dt r,k is interested, which denotes the clock difference between the individual GNSS timescale (GNSST) and the time and frequency reference. When the hardware delays caused by the receiver, antenna, and cables are calibrated [26,27], then the formula is expressed as follows: (11) It can be noted that the GNSS time scales plays the intermediary role in time and frequency transfer, which effectively overcome the limitation of geometric distance between two time and frequency references.…”

Section: Model Of the Df Time And Frequency Transfermentioning

confidence: 99%

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

Zhang

Gao

et al. 2021

Remote Sensing

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The modernized GPS, Galileo, and BeiDou global navigation satellite system (BDS3) offers new potential for time transfer using overlap-frequency (L1/E1/B1, L5/E5a/B2a) observations. To assess the performance of time and frequency transfer with overlap-frequency observations for GPS, Galileo, and BDS3, the mathematical models of single- and dual-frequency using the carrier-phase (CP) technique are discussed and presented. For the single-frequency CP model, the three-day average RMS values of the L5/E5a/B2a clock difference series were 0.218 ns for Galileo and 0.263 ns for BDS3, of which the improvements were 36.2% for Galileo and 43.9% for BDS3 when compared with the L1/E1/B1 solution at BRUX–PTBB. For the hydrogen–cesium time link BRUX–KIRU, the RMS values of the L5/E5a/B2a solution were 0.490 ns for Galileo and 0.608 ns for BDS3, improving Galileo by 6.4% and BDS3 by 12.5% when compared with the L1/E1/B1 solution. For the dual-frequency CP model, the average stability values of the L5/E5a/B2a solution at the BRUX–PTBB time link were 3.54∙× 10−12 for GPS, 2.20 × 10−12 for Galileo, and 2.69 × 10−12 for BDS3, of which the improvements were 21.0%, 45.1%, and 52.3%, respectively, when compared with the L1/E1/B1 solution. For the BRUX–KIRU time link, the improvements were 4.2%, 30.5%, and 36.1%, respectively.

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Section: Model Of the Df Time And Frequency Transfermentioning

confidence: 99%

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

Zhang

Gao

et al. 2021

Remote Sensing

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“…where the receiver clock offsets the clock difference between external atomic clock and GNSS timescale (GNSST) [26], which can be expressed as:…”

Section: Model Of Real-time Gnss Time and Frequency Transfer In Prototype Systemmentioning

confidence: 99%

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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“…The advantage of this approach is that the pseudo‐range observations carry time information and the CP observations are at millimetre noise levels [23]. The observation equation can be expressed as

({, \begin{matrix} 1em4pt \\ P = ρ + c \cdot ()(, normald t_{r} - normald t_{s}) + T_{trop} + δ + ε_{P} \\ normalΦ = ρ + c \cdot ()(, normald t_{r} - normald t_{s}) + T_{trop} + λ \cdot N + δ + ε_{Φ} \end{matrix})

where the subscripts r and s refer to the receiver and satellite, respectively; P and

normalΦ

denote the pseudo‐range and CP observations for the ionosphere‐free combination, respectively;

λ

is the wavelength; N is the observed satellite phase ambiguity;

ρ

is the geometric distance between the phase centre of the satellite and the receive antenna; c is the velocity of light in a vacuum;

normald t_{s}

is the satellite clock offset;

T_{trop}

denotes the tropospheric delay;

δ

is the hardware delay, which is mainly caused by the GNSS receiver, antenna, and corresponding cables that carry the internal electrical signal and can be calibrated in the area of the time and frequency transfer [24–26];

ε_{P}

and

ε_{Φ}

are the measurement noise for the pseudo‐range and CP observations, respectively;

normald t_{r}

denotes the receiver clock offset between the external time reference and the GNSS time scale, which is the most important parameter in time and frequency transfer applications. When precise IGS satellite orbit and clock products are used, the GNSS time scale refers to the IGST.…”

Section: Time and Frequency Transfer Using The Traditional Cp Technmentioning

confidence: 99%

Atomic clock modelling augmenting time and frequency transfer using carrier phase observation

Zhang

Gao

et al. 2020

IET Radar, Sonar & Navigation

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Study of time link calibration based on GPS carrier phase observation

Cited by 8 publications

References 14 publications

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

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

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

Atomic clock modelling augmenting time and frequency transfer using carrier phase observation

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