Machine Control and Gauidnes

4th International Conference on Machine Control & Guidance, March 19-20, 2014

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Accuracy Assessment Study of GNSS Precise Point Positioning for

Kinematic Positioning

Ashraf Abdallah , Volker Schwieger

University of Stuttgart Institute of Engineering Geodesy (IIGS)


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Structure

1. BASIC CONCEPTS

2. MOTIVATION

3. PROCESSING PROCEDURE

4. DATA ACQUSITION

5. RESULTS AND ANALYSIS

6. CONCLUSIONS


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1. BASIC CONCEPTS• PPP technique is the method that using of only

one GNSS receiver for positioning.• Precise satellite orbits and clock corrections

(e.g. From IGS and JPL).

• Antenna phase center variations for satellite and receiver.

• Phase wind up, solid earth tides, ocean loading effect and earth rotation.

GPS Ephem eris IGS JPL

3-D RM S Accuracy (cm )

Latency 3-D RM S Accuracy (cm )

Latency

Ultra-Rapid (predicted) ~5 cm real time - - Ultra-Rapid (estim ated) <3 cm 3 hours 5 cm < 2 hours Rapid (estim ated) ~2.5 cm 17 hours 3.5 cm Next-Day (16:00 UTC) Final (estim ated) ~2.5 cm ~13 days 2.5 cm < 14 days


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2. MOTIVATION

• Accuracy assessment study of kinematic PPP solution for two car kinematic trajectories .

• PPP solution Using GIPSY-OASIS software and CSRS-PPP online service.

• PPP solutions were evaluated with different periods of the initialization time (zero to sixty minutes); to establish the one needed reliable results.


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3. PROCESSING PROCEDURE• Observation data.• Data quality check

using TEQC software.• Differential GNSS

solution using Leica Geo Office software with SAPOS reference station.

• Divide the initialization time using TEQC software [from 60 min to 00 min].

• PPP solution using GIPSY-OASIS software and CSRS-PPP online service.


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3.1 GIPSY-OASIS software

• A scientific software for processing GPS data.

• published from JPL (Jet Propulsion Laboratory of NASA),

• deals with the static and kinematic GPS data.


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3.2 CSRS-PPP Online Service• Offered from the

Natural Resources of Canada (NRC) for PPP solution.

• Single or dual frequency

• Static or kinematic data.

• One of the most famous PPP online services.


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CSRS-PPP Online Service vs GIPSY-OASIS

4th International Conference on Machine Control & Guidance, March 19-20, 2014 9

3.3 Evaluation Methodology• Difference values () between the Leica Geo

Office PDGNSS results (M) as a reference solution and the PPP results (M’).

= M - M’Where (i) is the epoch number and (j) is east, north and height direction.• The RMSE (Root Mean Square Error) for the total

number of epochs (n).

• RMSE in 3 dimensions.


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4. DATA ACQUSITION• Two kinematic

trajectories , Stuttgart, Germany with sampling interval of 1 second.

• Using the measurement van of the Institute.

• The observations started with 60 minutes static data as an initialization time.

• 30 minutes of kinematic measurements.


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4.1 First data set

• A high number of satellites.• A little signal disturbance (cycle slips)


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4.2 Second data set

• More signal disturbance (cycle slips)


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5.1.1 First data using CSRS-PPP

• It provides RMSE in 3D of 11 cm with 10 minutes initialization times and reaches 5 cm in after 40 minutes.

• Height coordinates are the most varying parameter with different initialization time.

5. RESULTS AND ANALYSIS


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5.1.2 First data using GIPSY-OASIS

• GIPSY provide a gradually improvement in accuracy level.

• RMSE in east and north significantly improved from 00 to 20 minutes initialization times.

• It provides RMSE in 3D of 7 cm with 20 minutes initialization times.


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5.2.1 Second data using CSRS-PPP

• Horizontal direction: RMSE values from 3 to 12 cm.

• Height direction: RMSE values from 10 to 26 cm.• RMSE 3D: 10 cm with 60 minutes initialization

time. • The accuracy improved significantly from 20

minutes initialization time.


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5.2.2 Second data using GIPSY-OASIS [Gradient model]

• With standard tropospheric formula: un reliable results.

• Some trails to model tropospheric correction; gradient model characterizes the horizontal dimension of the tropospheric delay.

• First stable solution: from 20 minutes initialization times .

• Horizontal solution: around 10 cm RMSE and height direction has the most varying parameter


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5.2.2 Second data GIPSY-OASIS [Wet CSRS model]

• Wet parameters is high variable parameters and it should be predicted.

• Wet tropospheric values from CSRS-PPP online service.

• RMSE values for horizontal: 5 cm level from 10 minutes.

• RMSE 3D values : below 15 cm.


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6. CONCLUSIONS• GIPSY-OASIS software and CSRS-PPP online

service were used to determine a PPP solution.• The assessment study aims to evaluate the

effect of the initialization times on kinematic positioning.

The first data set has a good data quality. • GIPSY-OASIS software: RMSE 3D of 7 cm from 20

minutes initialization time.

• CSRS-PPP online service: RMSE 3D of 11 cm for 10 minutes initialization time ; reaches 5 cm for 40 minutes initialization time.


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6. CONCLUSIONSThe second data set has more signal disturbance

.• CSRS-PPP online service : RMSE for horizontal

directions from 3 to 12 cm ; for height direction from 10 to 26 cm.

• CSRS-PPP: a reliable solution from 20 minutes initialization times.

• GIPSY-OASIS : the standard tropospheric formula does not provide a suitable result.

• The gradient model : an improvement of PPP accuracy from 20 minutes initialization time.

• Wet parameters from CSRS-PPP : shows the best solution for this data set ; RMSE values in horizontal direction of 5 cm and 10 cm for height from 10 minutes initialization time.


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Thank you for your Attention!

QUESTIONS Contact:• M.Sc. Ashraf Abdallah• Institute of Engineering Geodesy, University of Stuttgart

• Geschwister-Scholl Str. 24D, 70174 Stuttgart, Germany

• Phone: +49 (0711) 685-84051 • Fax : +49 (0711) 685-84044 • Email : [email protected]

mailto:[email protected]

Machine Control and Gauidnes

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