extended’filter’for’real/0me’ mul0/gnss’orbit’determina0on’ - py0205 - chen.pdf ·...
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Extended Filter For Real-‐0me Mul0-‐GNSS Orbit Determina0on
Bingbing Duan Junping Chen
Shanghai Astronomical Observatory (SHAO)
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Content
Background
Extended filter
Real-time data analysis
Application to BDS system
Conclusion
Shanghai Astronomical Observatory
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Background
Shanghai Astronomical Observatory
Real-time orbits&clocks Broadcast R(m) T(m) N(m) 3D(m) GPS IIA 0.26 1.21 0.37 1.10 GPS IIR 0.14 1.04 0.42 0.52 GPS IIF 0.14 0.75 0.32 0.28 Galileo 0.63 2.65 2.29 1.62 BDS-I 0.50 2.42 1.31 0.87 BDS-M 0.50 2.42 1.31 0.87
Refer to igs.org and Montenbruck 2015
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Background
Shanghai Astronomical Observatory
Real-time orbits&clocks Broadcast R(m) T(m) N(m) 3D(m) GPS IIA 0.26 1.21 0.37 1.10 GPS IIR 0.14 1.04 0.42 0.52 GPS IIF 0.14 0.75 0.32 0.28 Galileo 0.63 2.65 2.29 1.62 BDS-I 0.50 2.42 1.31 0.87 BDS-M 0.50 2.42 1.31 0.87
Ultra-Rapid (predicted
half)
Accuracy Latency Updates
GPS Orbits 5cm Clocks 1.5ns
Real time UTC 03,09,15,21
Refer to igs.org and Montenbruck 2015
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Background
Shanghai Astronomical Observatory
Real-time orbits&clocks Broadcast R(m) T(m) N(m) 3D(m) GPS IIA 0.26 1.21 0.37 1.10 GPS IIR 0.14 1.04 0.42 0.52 GPS IIF 0.14 0.75 0.32 0.28 Galileo 0.63 2.65 2.29 1.62 BDS-I 0.50 2.42 1.31 0.87 BDS-M 0.50 2.42 1.31 0.87
Ultra-Rapid (predicted
half)
Accuracy Latency Updates
GPS Orbits 5cm Clocks 1.5ns
Real time UTC 03,09,15,21 IGS-RTS Accuracy Latency Updates
GPS Orbits 5cm Clocks 8cm
Real time -
Refer to igs.org and Montenbruck 2015
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Background
Shanghai Astronomical Observatory
For eclipsing satellites, regional GNSS system, orbits prediction accuracy suffers
Refer to Laurichesse et al, 2013
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Background
Shanghai Astronomical Observatory
Requirement of Real-time orbit determination u Attractive real-time applications, e.g., hazards monitoring, LEO orbit, troposphere & ionosphere u Constellation performance monitoring u Improve Signal in space (SIS) accuracy. Advantage of Multi-GNSS u More observations, better geometry, better precision, short convergence
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Real-time processing
Shanghai Astronomical Observatory
u Data cleaning Most post-processing algorithm cannot satisfy real-time data processing, single-difference combination are added. u Ambiguity resolution Future measurements are not available, ambiguities fixed at two consecutive epochs will be treated as known values. u Filter processing LSQ method changed to a batch filter (with capability to change update interval)
From post to real-time
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Extend filter
Shanghai Astronomical Observatory
• Filter update interval (arc length) is i epochs, all the linearizations are with respect to epoch 1; • Update initial orbit at epoch 1 and extrapolate orbit and to
epoch i; i (arc length) can be chosen flexibly u observation interval: the filter is a pure extended filter u 3 days: filter results is the same as least square solution
Filter design
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Extend filter
Shanghai Astronomical Observatory
Mathematics of the filter • State vector Processing
• Predict
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Priori info
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Real-time processing
Shanghai Astronomical Observatory
Data information
Data source : MGEX, 60 GPS sites, Green color stars 45 Galileo sites, Red color circles 36 Beidou sites, black color points
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Real-time processing
Shanghai Astronomical Observatory
Comparison between Filter with different interval and LSQ result
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Real-time processing
Shanghai Astronomical Observatory
Comparison between Filter with different interval and LSQ result
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Real-time processing
Shanghai Astronomical Observatory
Compare with Reference post-processing orbits
Mean 3D RMS: GPS: 7cm BDS-I: 57.2cm, BDS-M: 25.9cm,Galileo: 15.3cm
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Application to BDS system
Shanghai Astronomical Observatory
Improving BDS system SIS accuracy. Data length 2015.12.1-2015.12.28.
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Application to BDS system
Shanghai Astronomical Observatory
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Application to BDS system
Shanghai Astronomical Observatory
Civil signal SIS:URE,UDRE improved by 44%,
35%
URE:0.76(RMS) / 1.35 (95%)
UDRE: 0.26(RMS) / 0.39 (95%)
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Conclusion
Shanghai Astronomical Observatory
Ø Conclusion • Prototype system developed and validated • With flexibility to change filter steps
Ø Next steps • Solar radiation pressure parameter. • Ambiguity resolution between different constellations.
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Shanghai Astronomical Observatory
SHA: GNSS Analysis Center at SHAO h4p://www.shao.ac.cn/shao_gnss_ac
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Acknowledgement: Prof. Urs Hugentobler (TU Munich) and Oliver Montenbruck (DLR) hosted one-year visit and
valuable discussions