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Multifrequency Algorithms Multifrequency Algorithms forfor PPP: MAP3 PPP: MAP3

B. Moreno Monge (1), G. Rodriguez Caderot (2) and M. C. de Lacy (3)

(1) GFZ German Research Center for Geosciences(2) University Complutense of Madrid (Spain)(3) University of Jaen (Spain)

Outline

(1)Global Navigation Satellite Systems (GNSS)

(2)Precise Point Positioning (PPP)

(3)Multifrequency Algorithms for PPP: MAP3

(4)Numerical Tests

(5)Conclusions

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Global Navigation Satellite Systems (GNSS)

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Designed in the 70sMilitary → they have provided a wide variety of services

Signals in 2 frequencies

Global Navigation Satellite Systems (GNSS)

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In development

Signals in 3 frequencies

Global Navigation Satellite Systems (GNSS)

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Designed in the 70sMilitary → they have provided a wide variety of services

Signals in 2 frequencies

GPS and GLONASS in modernization process

→ They will include the triple frequency

Global Navigation Satellite Systems (GNSS)

System Current # sat Future # sat Frequencies Full Capability

GLONASS 23 24 G1 G2 G3 2011

Galileo 2 + 2 Giove 30 E1 E5 E6 2014

Mod. GPS 9 + 22 32 L1 L2 L5 2018

COMPASS 9 35 B1 B2 B3 2020

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Global Navigation Satellite Systems (GNSS)

System Current # sat Future # sat Frequencies Full Capability

GLONASS 23 24 G1 G2 G3 2011

Galileo 2 + 2 Giove 30 E1 E5 E6 2014

Mod. GPS 9 + 22 32 L1 L2 L5 2018

COMPASS 9 35 B1 B2 B3 2020

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Compatible and interoperable

→ allow the users to combine signals from different systems for their position determination

Precise Point Positioning (PPP)

● PPP is a positioning technique providing precise and accurate receiver position from undifferenced GNSS code and phase observations and precise satellite products.

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Precise Point Positioning (PPP)

● PPP is a positioning technique providing precise and accurate receiver position from undifferenced GNSS code and phase observations and precise satellite products.

● Great flexibility● Accurate results

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Precise Point Positioning (PPP)

● PPP is a positioning technique providing precise and accurate receiver position from undifferenced GNSS code and phase observations and precise satellite products.

● Great flexibility● Accurate results● In general, the accuracy in the

PPP is:At dm-level in kinematic mode

At cm-level in static mode (mm-level after 24 h observation)

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Precise Point Positioning (PPP)

● PPP software:

– CSRS-PPP (NRCan) www.geod.nrcan.gc.ca

– MagicGNSS (GMV) http://magicgnss.gmv.com/

– APPS (JPL) http://apps.gdgps.net/

– BSW v.5.0 http://www.bernese.unibe.ch/

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Precise Point Positioning (PPP)

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

● PPP software:

– CSRS-PPP (NRCan) www.geod.nrcan.gc.ca

– MagicGNSS (GMV) http://magicgnss.gmv.com/

– APPS (JPL) http://apps.gdgps.net/

– BSW v.5.0 http://www.bernese.unibe.ch/

Precise Point Positioning (PPP)

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

● PPP software:

– CSRS-PPP (NRCan) www.geod.nrcan.gc.ca

– MagicGNSS (GMV) http://magicgnss.gmv.com/

– APPS (JPL) http://apps.gdgps.net/

– BSW v.5.0 http://www.bernese.unibe.ch/

Precise Point Positioning (PPP)

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

● PPP software:

– CSRS-PPP (NRCan) www.geod.nrcan.gc.ca

– MagicGNSS (GMV) http://magicgnss.gmv.com/

– APPS (JPL) http://apps.gdgps.net/

– BSW v.5.0 http://www.bernese.unibe.ch/

Precise Point Positioning (PPP)

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● PPP software:

– CSRS-PPP (NRCan) www.geod.nrcan.gc.ca

– MagicGNSS (GMV) http://magicgnss.gmv.com/

– APPS (JPL) http://apps.gdgps.net/

– BSW v.5.0 http://www.bernese.unibe.ch/

Precise Point Positioning (PPP)

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

● PPP software:

– CSRS-PPP (NRCan) www.geod.nrcan.gc.ca

– MagicGNSS (GMV) http://magicgnss.gmv.com/

– APPS (JPL) http://apps.gdgps.net/

– BSW v.5.0 http://www.bernese.unibe.ch/

Only able to process GPS and GLONASS data in 1 or 2 frequenciesApply the ionofree linear combination → limits the positioning to the double frequency

It is necessary to design new algorithms adapted to the characteristics of the future GNSS scenario

Multifrequency Algorithms for PPP: MAP3

MAP3MAP3

New and original algorithmsNew and original algorithms

to perform to perform static PPPstatic PPP

from from multifrequency multifrequency observationsobservations

Allow to combine observations Allow to combine observations from different satellite systemsfrom different satellite systems

They can be used in the future GNSS scenario: Galileo, modernized GPS, GLONASS, They can be used in the future GNSS scenario: Galileo, modernized GPS, GLONASS, etcetc

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Multifrequency Algorithms for PPP: MAP3

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MAP3 -1

MAP3 -2

Multifrequency Algorithms for PPP: MAP3

Undifferenced multifrequency observations:Code Pi

s

Phase Lis

s = 1, 2, …, ni = 1, 2, 3, ...

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MAP3 -1

Multifrequency Algorithms for PPP: MAP3

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Undifferenced multifrequency observations:Code Pi

s

Phase Lis

s = 1, 2, …, ni = 1, 2, 3, ...

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

Smoothed pseudodistan-ces ρs

Ionospheric delays J1Initial ambiguities βi

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MAP3 -1

Multifrequency Algorithms for PPP: MAP3

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MAP3 -2

Smoothed pseudodis-tances ρs

Ionospheric delays J1Initial ambiguities βi

Multifrequency Algorithms for PPP: MAP3

Station coordinates (δX, δY, δZ)Clock offset dtr

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MAP3 -2

Multifrequency Algorithms for PPP: MAP3

GPS observables (Euler and Goad, 1991)

Pi(t), Li (t): code and phase

ρ(t) : pseudodistances

J1(t) : ionosferic delay in f1

βi : initial ambiguities (constant, real)

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Pi(t)=ρ(t)+k1i J 1(t)+νP i=1, 2Li(t)=ρ(t)−k1i J 1(t)+βi+νL

ρ(t)=D (t )+c (dtr−dt s)+Trop

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

Mathematical Model

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P (t )=A1ξ (t)+νP

L(t)=A2ξ (t)+β+νL

P (t )=(P1(t )P2(t )P3(t )

) L(t )=(L1(t)L2(t)L3(t)

) A1=(1 11 k12

1 k13) A2=(

1 −11 −k 12

1 −k 13) ξ (t )=( ρ(t)

J 1(t)) β=(β1

β2

β3)

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

For an observation period of nt epochs

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MAP3 -1

Multifrequency Algorithms for PPP: MAP3

Stochastic Model

νP : order of dm (20 cm)

νL : order of mm (2 mm)

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QP=(νP1

0 0

0 νP20

0 0 νP3

) QL=(νL1

0 0

0 νL20

0 0 νL3

)

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

Stochastic Model

νP : order of dm (20 cm)

νL : order of mm (2 mm)

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Not realistic → take into account sat. elevationNot realistic → take into account sat. elevation

QP=(νP1

0 0

0 νP20

0 0 νP3

) QL=(νL1

0 0

0 νL20

0 0 νL3

)

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

MAP3-1 expressions

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

MAP3-1 expressions

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Initial Phase ambiguities

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

MAP3-1 expressions

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Smoothed pseudoditancesIonospheric delays

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

MAP3-1 expressions

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Covariance matrices

MAP3 -1

Multifrequency Algorithms for PPP: MAP3

Position estimation

(Xs,Ys,Zs,dts) : Precise products must be used

Trops: is corrected with a model (Hopfield, Saastamoinen,etc)

→ a correction must be estimated every 2 hours ZWD

MAP3 -2

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ρs(t)=Ds(t)+c (dt r(t)−dt s(t))+Trops(t)+ν

Ds=√(X s

−X r)2+(Y s

−Y r)2+(Z s

−Z r)2

Multifrequency Algorithms for PPP: MAP3

Mathematical Model

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(X0,Y0,Z0) : A priori station position

MAP3 -2

Multifrequency Algorithms for PPP: MAP3

Mathematical Model

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Int : identity matrixρ0 : a priori distance

MAP3 -2

Multifrequency Algorithms for PPP: MAP3

Stochastic Model

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MAP3 -2

Multifrequency Algorithms for PPP: MAP3

Stochastic Model

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MAP3 -2

Multifrequency Algorithms for PPP: MAP3

Stochastic Model

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MAP3 -2

Multifrequency Algorithms for PPP: MAP3

MAP3-2 expressions

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MAP3 -2

Multifrequency Algorithms for PPP: MAP3

MAP3-2 expressions

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Station coordinatesTropo delay

MAP3 -2

Multifrequency Algorithms for PPP: MAP3

MAP3-2 expressions

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Station clock offset

MAP3 -2

Multifrequency Algorithms for PPP: MAP3

MAP3-2 expressions

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Covariance matrices

MAP3 -2

Multifrequency Algorithms for PPP: MAP3

Combination of different satellite systems

ISB estimation

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MAP3 -2

Numerical Tests

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Scenario 2. GPS and GIOVE

Scenario 1. GPS double frequency

Numerical Tests

Observations from USN3 (IGS)

Scenario 1. GPS double frequency

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Numerical Tests

Observations from USN3 (IGS)

2-hours

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Scenario 1. GPS double frequency

Numerical Tests

Observations from USN3 (IGS)

2-hours

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21 different days

Positioning error with MAP3

Scenario 1. GPS double frequency

Numerical Tests

Observations from USN3 (IGS)

2-hours

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21 different days

Positioning error with MAP3

2 cm

Scenario 1. GPS double frequency

Numerical Tests

Observations from USN3 (IGS)

2-hours

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21 different days

Positioning error with MAP3

2 cm

4 cm

Scenario 1. GPS double frequency

Numerical Tests

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Scenario 1. GPS double frequency

Numerical Tests

2-hours

RMS of the error in positioning (cm)

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Scenario 1. GPS double frequency

Numerical Tests

24-hours

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Scenario 1. GPS double frequency

Numerical Tests

24-hours

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7 mm

Scenario 1. GPS double frequency

Numerical Tests

24-hours

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1.4 cm

7 mm

Scenario 1. GPS double frequency

Numerical Tests

24-hours

RMS of the error in positioning (cm)

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Scenario 1. GPS double frequency

Numerical Tests

● GESS stations● GPS P1, P2 + GIOVE E1, E5b, E5a+b

Scenario 2. GPS and GIOVE

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Numerical Tests

● GESS stations● GPS P1, P2 + GIOVE E1, E5b, E5a+b● 2-hours● Precise products from Galileo

Processing Center (GPC)

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Scenario 2. GPS and GIOVE

Numerical Tests

● GESS stations● GPS P1, P2 + GIOVE E1, E5b, E5a+b● 2-hours● Precise products from Galileo

Processing Center (GPC)

GIOVE observations● ISB estimated● Electronic delays

corrected

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Scenario 2. GPS and GIOVE

Numerical Tests

● GESS stations● GPS P1, P2 + GIOVE E1, E5b, E5a+b● 2-hours● Precise products from Galileo

Processing Center (GPC)

GIOVE observations● ISB estimated● Electronic delays

corrected

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Systematic variations have been found in the GESS code observations depending on satellite direction and signal (Crisci et al., 2007) and a low multipath rejection (Simsky et al., 2008)

Systematic variations have been found in the GESS code observations depending on satellite direction and signal (Crisci et al., 2007) and a low multipath rejection (Simsky et al., 2008)

Scenario 2. GPS and GIOVE

Numerical Tests

GPS-only GPS+GIOVE

RMS of the error in positioning (cm)

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Scenario 2. GPS and GIOVE

Conclusions

● MAP3 constitutes a new and original strategy to perform static PPP from multi-system and multifrequency observations

● Its flexibility is an advantage w.r.t the current PPP SW● MAP3 are able to process modernized GPS and

Galileo/GIOVE data along with IGS and GPC products

● In general, MAP3 provides an accuracy in positioning of 2.5 cm after 2 hours observation and of 7 mm in 1 day

● These results are at the same level as the online PPP programs and better results are obtained in short observation periods

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Conclusions

● When processing GESS observations, the error in the estimated positions reached up to 15 cm, due to the systematic variations detected in the code observations and the high multipath, problems that will be solved after the installation of new antennas

● The combination of GPS and GIOVE data improved the accuracy in the positioning in almost 2 cm in every component with respect to the GPS-only solution

Continue analysing the improvements in the positioning due to the introduction of the new Galileo satellites

Analyse the improvement in positioning with the triple frequency

Study the influence and correction of electronic biases

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Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012

Thank you for your attention!Thank you for your attention!

beatrizmorenomonge@gmail.comgrc@mat.ucm.esmclacy@ujaen.es

References

● M. Crisci, M. Hollreiser, M. Falcone, M. Colina, and J. Giraud. GIOVE mission sensor station performance characterization: overview of the results. In ION GNSS, 2007.

● A. Simsky, D. Mertens, J. M. Sleewaegen, M. Hollreiser, and M. Crisci. Experimental Results for theMultipath Performance of Galileo Signals Transmitted by GIOVE-A Satellite. International Journal of Navigation and Observation, Article ID 416380, 2008. doi: 10.1155/2008/41638.

● H. J. Euler and C. C. Goad. On optimal filtering of GPS dual frequency observations without using orbit information. Bulletin Geodesique, 65:130–143, 1991.

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Multifrequency Algorithms for PPP: MAP3

For an observation period of nt epochs

MAP3 -1

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Observations must be free from cycle slipsObservations must be free from cycle slips

Multifrequency Algorithms for PPP: MAP3

MAP3-1 expressions

MAP3 -1

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L, P: mean of phase and code observationsN-1 = M-1 – M-1 A2

T QL-1 (I3 + A2 M-1A2

T QL-1)-1 A2 M

-1

D-1 = I3 + A2 M-1A2T QL

-1 M = A1T QP

-1 A1

Multifrequency Algorithms for PPP: MAP3MAP3 -2

Auxiliar expressions

Geodaetische Woche 2012 Hannover 09.10 – 11.10.2012