Impact of Galileo-to-GPS-Time-Offset accuracy on multi-GNSS positioning and timing

Defraigne, Pascale; Pinat, E.; Bertrand, Bruno

doi:10.1007/s10291-021-01090-6

Cited by 17 publications

(9 citation statements)

References 15 publications

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“…Process noise for the pseudo-ambiguities is chosen in accordance with the broadcast ephemeris quality and allows at least partial compensation of the ephemeris errors (Carlin et al 2021). In the observation model, the receiver time offset is formulated to refer to one constellation, plus an additional parameter per constellation considering the "User XYTO" (Defraigne et al 2021). This value combines the receiver-specific inter-system biases (ISBs) with the XYTO system-time offset, and it is equal to zero by definition for the reference constellation.…”

Section: Methodsmentioning

confidence: 99%

UTC and GNSS system time access using PPP with broadcast ephemerides

et al. 2022

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The application of precise point positioning with broadcast ephemerides (PPP-BCE) is discussed as an alternative to the established all-in-view technique for multi-GNSS time transfer. It combines the use of broadcast ephemerides with low-noise carrier-phase observations for accessing GNSS system time scales and Coordinated Universal Time (UTC) with improved precision, and can be employed on stationary as well as mobile receivers in offline or real-time analyses. Using calibrated timing receivers, the method is shown to provide estimates of the GNSS-to-GNSS time offsets (XYTOs) with an accuracy at the 2 ns level. In the absence of prior calibrations, 0.5 ns consistency across different stations is achieved for GPS, Galileo, and BeiDou-3 after adjustment of systematic biases in comparison with calibrated reference stations or broadcast XYTO values. Furthermore, access to GNSS-specific UTC realizations can be obtained through predictions of the UTC offset from GNSS system time as provided in the broadcast ephemerides of individual constellations. The overall quality of the PPP-BCE-derived receiver clock offsets from UTC is assessed using calibrated receivers at various timing laboratories along with BIPM-provided UTC-UTC(k) measurements. Over the 1.5 years covered in the study, an accuracy of 1.8 ns for GPS and 2.5 ns for Galileo is demonstrated. For BeiDou, a slightly worse accuracy of 3 ns is obtained for a single timing laboratory over 9 months.

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Section: Methodsmentioning

confidence: 99%

UTC and GNSS system time access using PPP with broadcast ephemerides

et al. 2022

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“…In addition to timescale offsets, constellation-dependent biases in the receiver hardware need to be considered. The combined effect of system time differences and receiver-specific biases is commonly compensated by choosing one GNSS as time reference and estimating an inter-system bias (ISB; Hauschild, 2017), also called user Galileo-to-GPS Time Offset (GGTO; Defraigne et al, 2021), relative to this system for all remaining GNSS.…”

Section: Time References and Bias Handlingmentioning

confidence: 99%

“…Furthermore, consecutive sets of the daily updated GGTO parameters can have differences of several nanoseconds and cause discontinuities at such transitions. Defraigne et al (2021) assessed the impact of the GGTO on the navigation solution and came to the conclusion that, for high-precision GNSS receivers, a better performance could be achieved when estimating the ISB rather than fixing it to a known value. In the present study, a sufficient number of GNSS satellites from both constellations was always available to enable precise estimation of the ISB from dual-frequency code and phase observations within the navigation filter.…”

Section: Time References and Bias Handlingmentioning

confidence: 99%

Precise Onboard Time Synchronization for LEO Satellites

Kunzi

Montenbruck

2022

navi

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Next to positioning and navigation, global navigation satellite systems (GNSSs) are widely used for precise timing. In terrestrial applications, time synchronization is crucial for a wide range of critical infrastructure and services, including communication networks, power grids, and financial transactions. Here, GNSS offers an affordable way to achieve time synchronization with respect to Universal Time Coordinated (UTC) with accuracies up to the ten-nanosecond level.Timing is also an important requirement in many satellite missions, like the time-tagging of altimetry measurements, payload synchronization of satellites flying in a formation such as bistatic synthetic-aperture radar satellites, and synchronization of constellation-wide networks. The majority of today's active LEO satellites operate in the areas of remote sensing, telecommunications, and broadband services, where precise time information is mandatory. Furthermore, the feasibility of position, navigation, and timing (PNT) services from LEO constellations has been

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“…With the development of the global navigation satellite system (GNSS), GNSS time transfer is widely used in the elds of time scale maintenance, scienti c studies, and dense map optimization [1][2][3][4] with its advantages of global, all-day, being able to operate continuously, high precision, and exibility. In the future, it may also be combined with location-based service (LBS) for private needs [5,6], which can provide support for heterogeneous networks, indoor navigation, and in-vehicle Internet [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Modelling and Assessment of BDS-3 Real-time Precise Point Positioning Time Transfer Based on PPP-B2b Service

Tang

Lyu

Zeng

et al. 2022

Mathematical Problems in Engineering

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In 2020, users in and around China had access to a new real-time precise point positioning (RTPPP) service with the BeiDou global navigation satellite system (BDS-3) B2b (PPP-B2b) signal. In this study, the quality of PPP-B2b products is first assessed and compared with the CNAV1 broadcast ephemeris. Then a mode of BDS-3 PPP time transfer with PPP-B2b (B2b-RTPPP) is developed and evaluated in static and kinematic modes. The results demonstrate that the discontinuity of orbit is improved by applying the PPP-B2b, and its root mean square errors (RMSEs) are 0.081 m, 0.165 m, and 0.107 m in the radial, along-track, and cross-track components, respectively. The standard deviation (STD) of the PPP-B2b clock offset is 0.08 ns, greatly better than that of the broadcast clock offset. For time transfer, the type A uncertainty of the B2b-RTPPP solution is approximately 0.1 ns in static mode, and approximately 0.3 ns in kinematic mode. The B1I/B3I B2b-RTPPP time transfer solution performs better than the B1C/B2a solution. For frequency stability, the modified Allan deviation (MDEV) of the B2b-RTPPP solution is comparable to that of the post-processing solution. The B1C/B2a combination has better short-term frequency stability than B1I/B3I, while the long-term frequency stability of B1C/B2a is worse. In addition, the contribution of the differential code bias (DCB) to B2b-RTPPP time transfer is also investigated. The type A uncertainty of the B2b-RTPPP solution without DCB correction is worse than that of the B2b-RTPPP solution with DCB correction. The B1C/B2a B2b-RTPPP solution without DCB correction has better frequency stability than the B1I/B3I B2b-RTPPP solution.

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Impact of Galileo-to-GPS-Time-Offset accuracy on multi-GNSS positioning and timing

Cited by 17 publications

References 15 publications

UTC and GNSS system time access using PPP with broadcast ephemerides

UTC and GNSS system time access using PPP with broadcast ephemerides

Precise Onboard Time Synchronization for LEO Satellites

Modelling and Assessment of BDS-3 Real-time Precise Point Positioning Time Transfer Based on PPP-B2b Service

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