Assessment of Multiple GNSS Real-Time SSR Products from Different Analysis Centers

Wang, Zhiyu; Li, Zishen; Wang, Liang; Wang, Xiaoming; Yuan, Hong

doi:10.3390/ijgi7030085

Cited by 82 publications

(48 citation statements)

References 16 publications

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“…Wang et al analyzed streams generated by various ACs and according to that research, CLK51 performed the best in the RMS comparison (2.09, 3.29, and 2.74 cm in the radial, along, and cross-track direction) while IGS products were the worst (5.79, 8.04, and 7.02 cm, again in those three directions). In case of GLONASS satellites, RTS products were almost two times worse [15]. Accuracy of GPS clock products and GLONASS clock products is about 8 cm and 13 cm, respectively [11,13,16].…”

Section: Introductionmentioning

confidence: 91%

Space State Representation Product Evaluation in Satellite Position and Receiver Position Domain

Pelc‐Mieczkowska

Tomaszewski

2020

Sensors

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In Global Navigation Satellite Systems (GNSS) positioning, important terms in error budget are satellite orbits and satellite clocks correction errors. International services are developing and providing models and correction to minimize the influence of these errors both in post-processing and real-time applications. The International GNSS Service (IGS) Real-Time Service (RTS) provides real-time orbits and clock corrections for the broadcast ephemeris. Real-time products provided by IGS are generated by different analysis centres using different algorithms. In this paper, four RTS products—IGC01, CLK01, CLK50, and CLK90—were evaluated and analysed. To evaluate State Space Representation (SSR) products’ GPS satellites, the analyses were made in three variants. In the first approach, geocentric real-time Satellite Vehicle (SV) coordinates and clock corrections were calculated. The obtained results were compared with the final IGS, ESA, GFZ, and GRG ephemerides. The second approach was to use the corrected satellite positions and clock corrections to determine the Precise Point Position (PPP) of the receiver. In the third analysis, the impact of SSR corrections on receiver Single Point Position (SPP) was evaluated. The first part of the research showed that accuracy of the satellite position is better than 10 cm (average 3 to 5 cm), while in the case of clock corrections, mean residuals range from 2 cm to 17 cm. It should be noted that the errors of the satellites positions obtained from one stream differ depending on the reference data used. This shows the need for an evaluation of correction streams in the domain of the receiver position. In the case of PPP in a kinematic mode, the tests allowed to determine the impact that the use of different streams has on the final positioning results. These studies showed differences between specific streams, which could not be seen in the first study. The best results (3D RMS at 0.13 m level) were obtained for the CLK90 stream, while for IGC01, the results were three times worse. The SPP tests clearly indicate that regardless of the selected SSR stream, one can see a significant improvement in positioning accuracy as compared to positioning results using only broadcast ephemeris.

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Section: Introductionmentioning

confidence: 91%

Space State Representation Product Evaluation in Satellite Position and Receiver Position Domain

Pelc‐Mieczkowska

Tomaszewski

2020

Sensors

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“…European Space Agency's Space Operations Centre in Darmstadt, Germany (ESA/ESOC), Deutsches GeoForschungs Zentrum (GFZ), GMV Aerospace and Defense (GMV), Natural Resources Canada (NRCAN), and Wuhan University WUHAN. Real-time PPP was assessed for static and kinematic applications using GPS only [13], GPS + GLONASS [14], GPS + GLONASS + BeiDou [15], and GPS + GLONASS + Galileo + BeiDou [10] [16] [17]. Galileo-only PPP and its contribution to GPS PPP were investigated using the final precise ephemeris for both static and post-processed kinematic modes [18].…”

Section: Centre National D'etudes Spatiales (Cnes) German Aerospace mentioning

confidence: 99%

“…Alternatively, precise point positioning (PPP) provides positioning solution accuracy at the centimeter-level in static mode and at the decimeter-level in kinematic mode for a single GNSS receiver using international GNSS service (IGS) rapid or final precise ephemeris [6] [7] [8] [9]. However, the required high positioning accuracy can only be achieved in post-processing mode due to the latency of the precise ephemeris [10]. In order to meet the growing needs for reliable real-time PPP, a real-time working group (RTWG) was established by IGS in 2001 and a real-time service (IGS-RTS) project was initially operated in 2011 in order to provide precise orbit and clock products and GNSS observations [11].…”

Section: Introductionmentioning

confidence: 99%

Real-Time GPS/Galileo Precise Point Positioning Using NAVCAST Real-Time Corrections

Elmezayen¹,

El-Rabbany²

2019

POS

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Real-time precise point positioning (PPP) is possible through the use of real-time precise satellite orbit and clock corrections, which are available through a number of organizations including the International GNSS Service (IGS) real-time service (IGS-RTS). Unfortunately, IGS-RTS is only available for the GPS and GLONASS constellations. In 2018, a new real-time service, NAVCAST, which provides real-time precise orbit and clock corrections for the GPS and Galileo constellations, was launched. In this research, the potential performance of real-time PPP which makes use of NAVCAST real-time corrections is analyzed using various static and kinematic datasets. In the static dataset, 24 hours of observations from eight IGS stations in Canada over three different days were utilized. The static results show that the contribution of Galileo satellites can improve the positioning accuracy, with 30%, 34%, and 31% in east, north, and up directions compared to the GPS-only counterparts. In addition, centimeter-level positioning accuracy in the horizontal direction and decimeter-level positioning accuracy in the vertical direction can be achieved by adding Galileo observations. In the kinematic dataset, a real vehicular test was conducted in urban and suburban combined areas. The real-time kinematic GPS/Galileo PPP solutions demonstrate an improvement of about 53%, 45%, and 70% in east, north, and up directions compared to the GPS-only counterparts. It is shown that the real-time GPS/Galileo PPP can achieve a sub-decimeter horizontal positioning accuracy and about meter-level vertical positioning accuracy through the use of NAVCAST real-time corrections.

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“…The process of the RT-PPP time and frequency transfer using the clock model is shown in Figure 2. It mainly includes two parts, as follows: (1) We obtain the observations from the receiver (connected to their time and frequency generator, a 1 PPS signal and a 5/10 MHz frequency signal), broadcast ephemeris and state space representation (SSR) corrections from IGS/ACs [25][26][27]. (2) If the data is not interrupted, it will go directly to RT-PPP processing to calculate the difference between the local time UTC (i) and the reference time (ref).…”

Section: The Clock Modelmentioning

confidence: 99%

An Approach to a Clock Offsets Model for Real-Time PPP Time and Frequency Transfer During Data Discontinuity

Qin

Pei

2019

Applied Sciences

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To resolve the dilemma in any post-processing strategy, i.e., the difficulty of monitoring the real-time time and frequency signals in a timely manner, real-time GPS time and the frequency transfer have recently become trending topics. Unfortunately, data interruption occurs when conducting real-time time transfer, sometimes from unexpected reasons. In this study, to ensure the stability and precision of real-time time transfer, an adaptive prediction model and a between-epoch constraint receiver clock model are applied as the mathematic models. The purpose of prediction is to solve the ambiguity from re-convergence when the data reappear. Moreover, compared to the conventional method, the between-epoch constraint receiver clock model is employed in this study to consider the correlation of epoch-wise clock parameters to avoid wasting useful information. The simulation data and real data are compared to verify the performance of the new approach. The simulation data for 165 days are designed with random daily interruptions of 10, 30, 60 and 90 min. Real data from 12 days is captured from the incomplete data in routine observation records. Ignoring the simulation data and real data, the investigation of six stations shows that the results with the between-epoch constraint receiver clock model were smoother than those with a white noise model. With an adaptive prediction model and the between-epoch constraint receiver clock model, the simulation results illustrate that the average root mean squares (RMS) values of all the stations are significantly reduced, i.e., by 66.03% from 0.43 to 0.14 ns, by 64.91% from 0.44 to 0.15 ns, by 57.47% from 0.43 to 0.18 ns, and by 51.67% from 0.44 to 0.21 ns for the 10, 30, 60 and 90 min data interruptions, respectively. The stability of all the stations is improved by at least 50%. The improvement increases to 100% for short-term stability. The real results show that the stability of four links is boosted by at least 5%. The model proposed in this paper is more effective in producing short-term stability than long-term stability.

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Assessment of Multiple GNSS Real-Time SSR Products from Different Analysis Centers

Cited by 82 publications

References 16 publications

Space State Representation Product Evaluation in Satellite Position and Receiver Position Domain

Space State Representation Product Evaluation in Satellite Position and Receiver Position Domain

Real-Time GPS/Galileo Precise Point Positioning Using NAVCAST Real-Time Corrections

An Approach to a Clock Offsets Model for Real-Time PPP Time and Frequency Transfer During Data Discontinuity

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