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2013 Western Australia Surveying Conference

BeiDou? First Australian results of BeiDou + GPS positioning Dennis Odijk , Robert Odolinski, Nandakumaran Nadarajah, Boris Padovan, Peter Teunissen GNSS Research Centre, Curtin University. 2013 Western Australia Surveying Conference. Presentation Outline. BeiDou What is it?

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2013 Western Australia Surveying Conference

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  1. BeiDou? First Australian results of BeiDou + GPS positioning Dennis Odijk, Robert Odolinski, Nandakumaran Nadarajah, Boris Padovan, Peter Teunissen GNSS Research Centre, Curtin University 2013 Western Australia Surveying Conference

  2. Presentation Outline BeiDou? First Australian results of a combined … • BeiDou • What is it? • Constellation + Signals • Time and Coordinate Systems • First ever results of Beidou+GPS, computed by GNSS Research Centre: • Single Point Positioning (SPP) • Real-Time Kinematic Positioning (RTK) • Attitude determination (Pitch, Roll and Yaw) • Conclusions

  3. BeiDou – What is it? BeiDou? First Australian results of a combined … 北斗 Big Dipper or Plough, Northern Dipper Chinese satellite navigation system Demonstration system (BeiDou-1) completed in 2003 Second generation under construction (BeiDou-2; previously known as COMPASS) SIS ICD released in December 2012 BeiDou signals will be free of charge Full global constellation expected in 2020

  4. BeiDou – Constellation Sky plots for Perth BeiDou? First Australian results of a combined … • Operational constellation: • 35 satellites (GPS currently 31 - MEO) • 5 Geosynchronous Earth Obiter (GEO) • 3 Inclined GeoSynchronous Orbiter (IGSO) • 27 Medium Earth Orbiter (MEO) • Global coverage • Current (2013) Constellation: • 14 satellites • 5 GEO, 5 IGSO and 4 MEO satellites • Fully operational in the Asia Pacific region

  5. BeiDou – Signal Frequencies B1: 1561.098 MHz 19.20 cm B2: 1207.140 MHz 24.83 cm B3: 1268.520 MHz 23.63 cm L1: 1575.420 MHz 19.03 cm L2: 1227.600 MHz 24.42 cm L5: 1176.450 MHz 25.48 cm B2 B3 B1 BEIDOU BeiDou, GPS (and Galileo) signals are based on Code Division Multiple Access (CDMA) BeiDou? First Australian results of a combined … BeiDou: (Modernized) GPS:

  6. BeiDou – Time and Coordinate Systems BeiDou? First Australian results of a combined … BeiDou Time System: Beidou time (BDT) is synchronized with UTC within 100 ns Offset BDT and GPS time (GPST)/Galileo time (GST) is broadcast by satellites BeiDou Coordinate System: BeiDou uses China Geodetic System 2000 (CGS2000) Coincides with ITRF at few centimetre level; for most (surveying) applications difference between CGS2000 and ITRF can be ignored

  7. Combined BeiDou + GPS: Increased model strength and availability Suitable for e.g.: Developing and operating mines Agriculture (wheat belt in dark yellow) BeiDou? First Australian results of a combined …

  8. GNSS Satellite Availability in Challenging Environments “urban canyons” open pit mines BeiDou? First Australian results of a combined …

  9. BeiDou + GPS: Single Point Positioning (SPP) B1 BEIDOU. BeiDou? First Australian results of a combined … 24 h of data (07/07/12) tracked at Curtin’s permanent GNSS station (Trimble NetR9) Single-frequency Beidou (B1 code) + GPS (L1 C/A code) data used; cut off = 10 deg Satellite orbits/clocks from nav. message Estimate parameters: 3D position + 1 receiver clock error per constellation Position errors computed by subtracting estimated position from known coordinates

  10. BeiDou + GPS: Real-Time Kinematic (RTK) Positioning CUTA (Left; reference) and CUTT (Right; rover) GNSS antennas, baseline distance ~1 km BeiDou? First Australian results of a combined … Relative (2 receivers) positioning based on code (pseudorange) and carrier phase Integer carrier-phase ambiguity resolution (IAR) = key to high-precision (mm-cm level) positioning Short baseline: elimination of clocks + atmospheric errors Most challenging: single-frequency BeiDou (B1 code) + GPS (L1 C/A code) single-epoch RTK Double-differenced observations with unknown parameters: 3D relative position + double-differenced phase ambiguities per constellation

  11. Single-frequency RTK ambiguity resolution + positioning results – cut-off elevation: 35 deg BeiDou-only B1 24 h of data (21/04/13) BeiDou? First Australian results of a combined …

  12. Single-frequency RTK ambiguity resolution + positioning results – cut-off elevation: 35 deg GPS-only L1 24 h of data (21/04/13) BeiDou? First Australian results of a combined …

  13. Single-frequency RTK ambiguity resolution + positioning results – cut-off elevation: 35 deg BeiDou B1 + GPS L1 24 h of data (21/04/13) BeiDou? First Australian results of a combined …

  14. Beidou + GPS Attitude Determination Determination of the relative orientation between reference systems BeiDou? First Australian results of a combined …

  15. Beidou + GPS Attitude Determination 24 h of data (17/03/13) 8-m baseline Instantaneous ambiguity resolution success-rates LAMBDA: “standard” (RTK) ambiguity resolution; C-LAMBDA: baseline-constrained ambiguity resolution BeiDou? First Australian results of a combined …

  16. Conclusions BeiDou? First Australian results of a combined … • BeiDou is now operational in Asia-Pacific region and signals can be tracked by multi-GNSS receivers • Combined BeiDou+GPS: increased availability of satellites and frequencies • Data quality BeiDou ≈ GPS • First ever Australian combined BeiDou+GPS results were presented, computed using in-house software of Curtin’s GNSS Research Centre • Combined Beidou+GPS seems to be much more robust for single-frequency RTK positioning and attitude determination in challenging environments, compared to one constellation

  17. Acknowledgments BeiDou? First Australian results of a combined … This work has been executed in the framework of the CRC-SI Positioning Program Project 1.01 ”New carrier-phase processing strategies for achieving precise and reliable multi-satellite multi-frequency GNSS/RSS positioning in Australia” Curtin PhD student Mr Robert Odolinski (Robert.Odolinski@curtin.edu.au) for processing the SPP and RTK examples Curtin researcher Dr Nanthi Nadarajah (N.Nadarajah@curtin.edu.au) for processing the attitude examples

  18. More information? Contact: GNSS Research Centre, Department of Spatial Sciences, Curtin University Email: p.teunissen@curtin.edu.au BeiDou? First Australian results of a combined …

  19. Thanks for your attention! Questions? BeiDou? First Australian results of a combined …

  20. BeiDou + GPS: “DGNSS” Positioning CUTA (Left; reference) and CUTT (Right; rover) GNSS antennas, baseline distance ~1 km B1 BEIDOU L1 GPS B1 BEIDOU + L1 GPS BeiDou? First Australian results of a combined … Relative (2 receivers) code (pseudorange) based positioning Short baselines: reduction/elimination of orbit, clock + atmospheric errors Single-frequency BeiDou(B1 code) + GPS (L1 C/A code) data used Double-differenced observations with unknown parameters: 3D relative position Position errors of CUTT : computed by subtracting estimated position from known coordinates

  21. Single-frequency RTK ambiguity resolution + positioning results – cut-off elevation: 10 deg BeiDou-only B1 BeiDou? First Australian results of a combined …

  22. Single-frequency RTK ambiguity resolution + positioning results – cut-off elevation: 10 deg GPS-only L1 BeiDou? First Australian results of a combined …

  23. Single-frequency RTK ambiguity resolution + positioning results – cut-off elevation: 10 deg BeiDou B1 + GPS L1 BeiDou? First Australian results of a combined …

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