the contribution of beidou to multi- gnss precise point positioning · 2019. 10. 3. · 2 fugro...

The contribution of BeiDou to multi-GNSS Precise Point Positioning

Javier Tegedor, Ole Ørpen

Fugro Satellite Positioning AS

Geodesi- og hydrografidagene 2015, Sundvollen, 18-19 November 2015

www.fugro.com2

Fugro Precise Point Positioning services


• Fugro launched in 2009 the G2 service using GPS and GLONASS:

• Proprietary worldwide tracking network

• Real-time estimation of orbits/clocks

• Broadcast corrections using GEO satellites

• Maritime professional users

• Highly redundant service

• Decimeter level accuracy

• Following GNSS evolution, new services have been introduced in Q1 2015:

• G2+: ambiguity-fixed PPP

• G4: addition of BeiDou and Galileo

www.fugro.com3

G4 tracking network

• The legacy G2 reference station tracking network has been upgraded to G4 capability

• Fugro G4 receivers are tracking all BeiDou and Galileo open signals:

• Galileo: E1, E5a, E5b, E5a+b

• BeiDou: B1, B2, B3


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Fugro’s first Galileo Only Positioning, 18 March 2013

• Four IOV satellites used in Precise Point Positioning (PPP) at 10 cm level

• Fugro generated high accuracy Galileo orbit/clock data using Fugro’stracking network

Fugro tracking network in March 2013, yellow means Galileo capable stations


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Galileo current status

Satellite PRN Launch Status

IOV PFM E11 Oct 2011 OK

IOV FM2 E12 Oct 2011 OK

IOV FM3 E19 Oct 2012 OK

IOV FM4 E20 Oct 2012 Only transmitting in E1

FOC FM1 E18 Aug 2014 Non-nominal orbit

FOC FM2 E14 Aug 2014 Non-nominal orbit

FOC FM3 E22 Mar 2015 OK

FOC FM4 E26 Mar 2015 OK

FOC FM5 E24 Sept 2015 OK

FOC FM6 E30 Sept 2015 OK


• G4 system has been qualified for Galileo

• No Galileo corrections delivered to customers yet

• Galileo will be added to G4 when operational

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BeiDou status

• Regional coverage in Asia– 3 MEO (Medium Earth Orbit)– 5 IGSO (Inclined Geosynchronous Orbit)– 5 GEO (Geostationary Orbit)

• Full worldwide Coverage (30 satellites) by 2020

• Next generation BeiDou-3:• First satellite launched on March 31st

• 2 additional satellites launched on July

The new G4 service: multi-constellation PPP including GPS, Glonass, Galileo and BeiDou

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BeiDou status






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BeiDou status






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BeiDou, Chinese Satellite Navigation System






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BeiDou challenges

• Geometry

• Orbit determination for GEOs is particularly challenging due the static position with respect to the reference station network

• Satellite attitude:

• Orbit normal mode used by GEOs, and IGSO/MEOs at low β-angles


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GEO satellites - Orbit normal vs yaw-steering


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Challenges for BeiDou PPP


• Satellite antenna modelling

• Phase center offset (PCO) and variations (PCV) are needed for bothtranmitting and receiving antennas

-5

-4

-3

-2

-1

0

1

2

3

4

0 1 2 3 4 5 6 7 8 9 10 11 12 13

PC

V (

mm

)

Nadir angle (degrees)

MEO

IGSO

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Challenges for BeiDou PPP

• Frequency transition from B1 (1561.098 MHz) to L1 (1575.42 MHz)

• QPSK to MBOC

• Pending ICD update

• Operational challenges for customers

• Need to upgrade FW in the receivers in the field

Source: Navipedia


BeiDou TMBOC signals tracked by Javad Source: GpsWorld

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Orbit accuracy


• BeiDou MEO orbit accuracy is similar to Glonass

• Slightly worse for IGSOs

• Meter-level error for GEO (mainly along-track)

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Clock stabillity

• Short-term BeiDou clock stability is a bit worse than Galileo and GPS IIF clocks

• Computed Allan-deviations from real-time G4 1Hz clocks:


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Real-time G4 performance

• Real-time G4 performance on Perth (Australia), September 6th 2015

• Up to 30 satellites contribute to position estimation:

• G4 is significantly more robust than G2 thanks to the increased number of satellites


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Precise Point Positioning using BeiDou – Perth (Australia)

• The addition of GEO satellites to the G4 service allows to obtain 24/7 PPP using only BeiDou

• Very good horizontal accuracy (<10cm)• Vertical accuracy is a bit more variable due to GEO orbit

errors


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Real-time G4 performance

• The design of the BeiDou constellation allows to obtain 24/7 real-time PPP results in the Far East, when all BeiDou satellites are used

• Orbit accuracy for BeiDou GEO satellites limits BeiDou-only PPP performance

• BeiDou-only PPP is slightly worse than GPS, but still at decimeter level

• 24 hours horizontal position plots for GPS-only, BeiDou-only and G4


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Satellite visibility from Oslo 31 July 2015

Satellites used in solution:

BeiDou GEO SatelliteFugro

Broadcast Satellite

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G4 in Oslo 30-31 July 2015

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Advantages of multi-constellation PPP

• Increased accuracy and reduced convergence time

• More robustness against:• Interference• Scintillation• Partial sky visibility

• Better RAIM protection


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2 GPS + 2 BeiDou GEOs positioning


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Multi-GNSS Integration


• When Galileo and BeiDou are fully deployed, new positioning scenarios can be envisaged:

• Deliver two independent solutions

• Independent of single-system failure

• Integrity detection is possible by checking the two positions

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Conclusions


• Fugro introduced the G4 PPP service in 2015

• BeiDou is already an important contribution to multi-GNSS PPP

• Higher accuracy, robustness and availability

• On-going work

• B1 to L1 frequency transition

• Modelling improvements

• Additional GNSS provides an opportunity for improved performance

• Higher accuracy, reliability and faster convergence

• Independent solutions

www.fugro.com25 The contribution of BeiDou to multi-GNSS Precise Point Positioning

Thank you for your attention!

Javier Tegedor

GNSS Scientist

Fugro Survey Division

Email: [email protected]: www.fugrosatellitepositioning.com

the contribution of beidou to multi- gnss precise point positioning · 2019. 10. 3. · 2 fugro...

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