FUDS-ECSC Urban environment Training course 5 : GPS Bernard LORTIC - March 2006 FUDS- ECSC UR029

FUDS-ECSC Urban environment

Training course 5 :

GPS

Bernard LORTIC - March 2006

FUDS-ECSCUR029


➔GPSGPS SummarySummary

I.I. Location measure Location measure

II.II. Distances : geometry or time. Distances : geometry or time.

III.III. Positioning system in 2 dimensionsPositioning system in 2 dimensions

IV.IV. Accuracy- Errors Accuracy- Errors V.V. MaterialsMaterialsVI.VI. PracticePractice

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I. GPS

- GPS can measure the location of a point.

- I.E. : It can compute coordinates (X,Y,Z) on a determined ellipsoid and Datum.

- This geodesic system is WGS84.

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II. GPS : Measuring time to measure the geometry

- From Eratosthenes to satellites (or radar)we measure the distances by geometric processing.●Alidade●Total station●We measure angles and we compute by trigonometry

- with GPS we measure the time.

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II. GPS :- Geometric processing.

●Alidade

●Theodolite●

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II. GPS :- Geometric processing.

●Total station

●

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II. GPS

- Triangulation :

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●III. GPS - Little novel (by Pierre André

Chevalier ) Haute école technique et informatique de Bienne) :

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There was a country with a very smoky lake. Every week happened some disasters with the boats. So the king decided to instal a LPS (local positioning system).Composition : - spatial component : 3 guns.- control component : 4 very hight precision clocks. And a map.- users component : two good hears, a pen and a compass



Chevalier) Haute école technique et informatique de Bienne) :


There was a country with a very smoky lake. Every week happened some desasters with the boats. So the king decided to intal a LPS (local positionning sytem).

Composition : - spatial component : 3 guns guns.- control component : 4 very hight precision clocks.- users component : two good hears, a pen and a compas.



Chevalier)Haute école technique et informatique de Bienne) :


There was a country with a very smoky lake. Every week happened some disasters with the boats. So the king decided to instal a LPS (local positioning system).Composition : - spatial component : 3 guns guns.- control component : 4 very hight precision clocks.- users component : two good hears, a pen and a compass.



Chevalier)Haute école technique et informatique de Bienne) :


There was a country with a very smoky lake. Every week happened some disasters with the boats. So the king decided to instal a LPS (local positioning system).Composition : - spatial component : 3 guns guns.- control component : 4 very hight precision clocks.- users component : two good hears, a pen and a compass.

IV. GPSIV. GPS - - DatumDatumMathematical operations are available to transform the values from a Mathematical operations are available to transform the values from a datumdatum to an other one, if we know the relation for the location between to an other one, if we know the relation for the location between two referential ellipsoids. Practically we use the global WGS84 datum to two referential ellipsoids. Practically we use the global WGS84 datum to go from a datum to another one the differences are about 100 meters. go from a datum to another one the differences are about 100 meters. Ex : Formula Molodensky’’s

double dRn=m_dA/sqrt(1.-m_dE2*dSinLat*dSinLat);double dRm=m_dA*(1.-m_dE2)/pow(1.-m_dE2*dSinLat*dSinLat,1.5);double dDeltaLong=(-m_dDeltaX*dSinLong + m_dDeltaY*dCosLong)/((dRn+dHauteur)*dCosLat);dDeltaLong/=dMinuteToRadian;double dDeltaLat=-m_dDeltaX*dSinLat*dCosLong - m_dDeltaY*dSinLat*dSinLong + m_dDeltaZ*dCosLat;dDeltaLat=dDeltaLat + m_dDeltaA*(dRn*m_dE2*dSinLat*dCosLat)/m_dA;dDeltaLat=dDeltaLat + m_dDeltaF*(dRm*m_dAsurB + dRn*m_dBsurA)*dSinLat*dCosLat;dDeltaLat=dDeltaLat/(dRm + dHauteur);dDeltaLat/=dMinuteToRadian;double dDeltaH=m_dDeltaX*dCosLat*dCosLong + m_dDeltaY*dCosLat*dSinLong + m_dDeltaZ*dSinLat;dDeltaH=dDeltaH - m_dDeltaA*sqrt(1.-m_dE2*dSinLat*dSinLat) + m_dDeltaF*m_dBsurA*dRn*dSinLat*dSinLat;

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IV. GPSIV. GPS - -Positioning techniques are totally changed since the use of satellites.Positioning techniques are totally changed since the use of satellites.

●First studies in the 70s' by the DoD. (Department of First studies in the 70s' by the DoD. (Department of Defence).Defence).●Main purpose : global positioning system by satellite.Main purpose : global positioning system by satellite.●February 1978 : First GPS satellite.February 1978 : First GPS satellite.●1983 : Civil (non-military) access.1983 : Civil (non-military) access.●1990 : accuracy degradation.1990 : accuracy degradation.●1994 : declaration of operational approval.1994 : declaration of operational approval.●2000 : suppression of accuracy degradation.2000 : suppression of accuracy degradation.


IV. GPSIV. GPS - -Spatial segment : 24 satellites at 20000 Km height.Spatial segment : 24 satellites at 20000 Km height.● Revolution in 12 hours.Revolution in 12 hours.● Atomic clock for power and precision.Atomic clock for power and precision.● Time signal and ephemerides transmission.Time signal and ephemerides transmission.

Control segment : 5 ground stations.Control segment : 5 ground stations.● Satellites controlSatellites control● correction of location errors.correction of location errors.

User segment GPS receiversUser segment GPS receiversReceiver/satellite distance measure.Receiver/satellite distance measure.Users location computing.Users location computing.


IV. GPSIV. GPS - -GPS accuracy is now of three meters with all public receivers.GPS accuracy is now of three meters with all public receivers.The receiver user can choose the The receiver user can choose the datum datum to display the to display the coordinates.coordinates.Differential measures (with two GPS) allows to obtain millimetres Differential measures (with two GPS) allows to obtain millimetres accuracy.accuracy.

1of wave length

from 1 to 3 m

from 1 to 2 mm

Noise

Depends of ground featureMulti path

1 m Receiver

1 m Clock mistake

from 2 to 30 m Troposphere

From 0 to 50 m Ionosphere

Until 10 m Ephemeris

Disturbances which can affect the GPS data :Disturbances which can affect the GPS data :


CoordinatesCoordinatesRemember :Remember :

Projection and datum are strongly linked: the datum gives the right Projection and datum are strongly linked: the datum gives the right ellipsoid to use for the projection. (It is not allowed to project ellipsoid to use for the projection. (It is not allowed to project coordinates using a different ellipsoid which doesn’t correspond to coordinates using a different ellipsoid which doesn’t correspond to a given datum.)a given datum.)

Maps with the same projection but with different datum are not in Maps with the same projection but with different datum are not in coincidence. ( Displacement of some ten or hundredth meters).coincidence. ( Displacement of some ten or hundredth meters).

Maps with same datum but different projections doesn't coincide Maps with same datum but different projections doesn't coincide (displacement about hundred to thousands meters).(displacement about hundred to thousands meters).



V. GPS Ours tools

GARMIN GPS

Etrex

GPS 60

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V. GPS

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ETREX PAGES UP

DOWN

ENTER

ON/OFF


V. GPS

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ETREX With

« PAGES »

Select

« Menu »

Select « Marquer »


V. GPS

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ETREX Read the coordinates at the bottom of this pages

and write N° of the point (the name), X and Y in your note book.

We don't need of elevation.


V. GPS

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ETREX Before working :

We have to adjust the system with « reglages »

,


V. GPS

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ETREX Geodesic system is not in « system » but in « units »

,


V. GPS

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ETREX First select :projection : UTM

,


V. GPS

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ETREX After, select :the « datum »

Adindan or WGS84.

,


V. GPS

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GPS 60

Mark :

ON/OFF

Pages

Enter


V. GPS

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GPS 60

Number of satellites

Accuracy index


V. GPS

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GPS 60

Saving Waypoint

Name of waypoint

DateValues

SAVGLOBE SAVGLOBE (Software IRD)(Software IRD)SAVGIS little module to compute new coordinates in a new SAVGIS little module to compute new coordinates in a new projection or a new datum projection or a new datum


SAVGLOBE SAVGLOBE (Software IRD)(Software IRD)


SAVGLOBE SAVGLOBE (Software IRD)(Software IRD)


VI. Field practiceVI. Field practice








Baro X Y

Etrex Adindan 472823 998049ETREX wgs84 472919 998256

96 207

Gps60Adindan 472821 998051WGS84 472915 998258

94 207

VI. Field practice - VI. Field practice - Number 2 – GPS 60Number 2 – GPS 60


On Saturday 2006 Gizachew Berahu take a walk around the school with the GPS 60 from Garmin.He marked (with « mark »; « enter » ) some points in the middle of the streets. Coming back, he downloaded the values to the computer with the software Map source (from Garmin)



On Saturday 2006 Gizachew Berahu take a walk around the school with the GPS 60 from Garmin.He marked (with « mark »; « enter » ) some points in the middle of the streets. Coming back, we downloaded the values to the computer with the software Map source (from Garmin)

UTM Datum WGS 84

Name Description Position Altitude32 29/04/2006 11:50:50 473119 997491 2365 33 29/04/2006 11:51:57 473128 997506 2367 34 29/04/2006 11:52:41 473137 997514 2371 35 29/04/2006 11:53:41 473133 997554 2370 36 29/04/2006 11:54:29 473147 997560 2369 37 29/04/2006 11:55:00 473178 997562 2370 38 29/04/2006 11:56:01 473228 997577 2372 39 29/04/2006 11:59:23 473290 997549 2372 40 29/04/2006 12:00:24 473308 997599 2371 41 29/04/2006 12:01:42 473332 997681 2376 42 29/04/2006 12:02:16 473335 997717 2375 43 29/04/2006 12:02:39 473306 997714 2377 44 29/04/2006 12:03:27 473245 997706 2380 45 29/04/2006 12:04:13 473223 997702 2382 46 29/04/2006 12:05:44 473114 997698 2383 47 29/04/2006 12:09:03 473105 997494 2365



We can import the result in Savedit



We can import the result in Savedit



Obviously, the result is wrong. Ato Gezachew was walking in the streets !Why ?Beaucose of the reference system !













Process for downloading location data from Garmin GPS 60.Even the GPS 60 could display coordinates in datum Adindan, we can only download coordinates in WGS 84.1) Download the waypoints with « mapSources » conecting the GPS with a USB cable to your computer.2) Edit the text file to deleate some unusefull data et to put correct separator beteenw the fields.3) In Savedit ; open the data base « addis Abeba » in this case and choose in « map » the WGS 84 system.

Selected ReferencesSelected ReferencesBalmino G., Balmino G., Champ de pesanteur terrestre et géoïde. Principes, progrès et connaissance Champ de pesanteur terrestre et géoïde. Principes, progrès et connaissance actuelleactuelle, 1998, Bureau Gravimétrique International, Toulouse, France, 1998, Bureau Gravimétrique International, Toulouse, France

Beguin M., Pumain D., Beguin M., Pumain D., La représentation des données géographiquesLa représentation des données géographiques, 1994, CURSUS-Armand , 1994, CURSUS-Armand Colin, ParisColin, Paris

Botton S., Duquenne F., Egels Y., Even M., Willis P., Botton S., Duquenne F., Egels Y., Even M., Willis P., GPS, localisation et navigationGPS, localisation et navigation, 1998, , 1998, Hermès, ParisHermès, Paris

Bouteloup D., Bouteloup D., Cours de géodésieCours de géodésie, École nationale des sciences géographiques,2004, IGN-, École nationale des sciences géographiques,2004, IGN-ENSG, ParisENSG, Paris

Cazenave A., Feigl K., Cazenave A., Feigl K., Formes et mouvements de la TerreFormes et mouvements de la Terre, 1994, Ed.Belin-CNRS, 1994, Ed.Belin-CNRS

Dufour J.P., Dufour J.P., Cours d’introduction à la géodésieCours d’introduction à la géodésie, École nationale des sciences géographiques, , École nationale des sciences géographiques, 1998, IGN-ENSG1998, IGN-ENSG

Iliffe J.C., Datums and map projections, CRC Press, 2000Iliffe J.C., Datums and map projections, CRC Press, 2000Lefort J., L’aventure cartographique, Belin-Pour la Science, 2004Lefort J., L’aventure cartographique, Belin-Pour la Science, 2004

Levallois J.J., Boucher C., Bourgoin J., Comolet-Tirman A., Robertou A., Levallois J.J., Boucher C., Bourgoin J., Comolet-Tirman A., Robertou A., Mesurer la Terre : 300 Mesurer la Terre : 300 ans de géodésie française, De la toise du Châtelet au satelliteans de géodésie française, De la toise du Châtelet au satellite , 1988, Association française de , 1988, Association française de topographie, Presse de l’École Nationale des Ponts et Chaussées, AFT, Paristopographie, Presse de l’École Nationale des Ponts et Chaussées, AFT, Paris

Magellan Systems Corporation, Magellan Systems Corporation, User guide for the Magellan GPS ProMARK X-User guide for the Magellan GPS ProMARK X-CMCM, 1997, 1997Souris M., Souris M., Mesurer la TerreMesurer la Terre, dans , dans Principes et algorithmes des SIGPrincipes et algorithmes des SIG, 2002, 2002


Documents

FUDS-ECSC Urban environment Training course 5 : GPS Bernard LORTIC - March 2006 FUDS- ECSC UR029