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Mr.Samniang Suttara B.Eng. (Civil), M.Eng. (Survey) Topcon Instruments (Thailand) Co.,Ltd.

Satellite Surveying. Mr.Samniang Suttara B.Eng. (Civil), M.Eng. (Survey) Topcon Instruments (Thailand) Co.,Ltd. E-Mail : gps@topcon.co.th Tel. 08-1821-1297. G lobal N avigation S atellite S ystem. What is GNSS ?. ADVANTAGE. - Accuracy from meter to millimeter - Everywhere

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Mr.Samniang Suttara B.Eng. (Civil), M.Eng. (Survey) Topcon Instruments (Thailand) Co.,Ltd.

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  1. Satellite Surveying Mr.Samniang Suttara B.Eng. (Civil), M.Eng. (Survey) Topcon Instruments (Thailand) Co.,Ltd. E-Mail : gps@topcon.co.th Tel. 08-1821-1297

  2. Global Navigation Satellite System What is GNSS ? ADVANTAGE - Accuracy from meter to millimeter - Everywhere - Everytime - One system coordination - Many user segment - No expenses

  3. NAVSTAR GPS (Global Positioning System) By USA. GLONASS (GLObal NAvigation Satellite System or GLObalnaya NAvigatsionnaya Sputnikovaya Sistema) By Russian. GALILEO By The European Space Agency (ESA) COMPASS By China. GNSS Provider?

  4. USA Russia Constellation Technology • Launched: 1978 • 24 Satellite Constellation • Launched: 1982 • Current Satellite Constellation: 18 • Planned Constellation: 24 E.U. • Test Satellite Launched: Dec. 2005 • Current Satellite Constellation: 2 • Planned Constellation: 30 Satellites

  5. Constellation Technology COMPASS

  6. Satellites • GPS Satellites 2. GLONASS Satellites

  7. Satellites 3. GALILEO Satellites 4. COMPASS Satellites

  8. GLONASS GPS Number of Satellites 24 (24) 24 (27) Launch Vehicle Proton k/DM-2 Delta 2-7925 Satellite Per Launch 3 1 Orbital Planes 3 6 Orbit Inclination 64.8 55 Orbit Altitude 19100 km 20200 km Orbital Period 11 h 15 min 11 h 58 min Ephemerides Pos/Vel/Acc Keplerian Reference Ellipsoid PZ90 WGS84 Carrier Freq. L1 1602.5625 - 1615.5 MHz 1575.42 MHz Carrier Freq. L2 1246.4375 – 1256.5 MHz 1227.60 MHz C/A-code(L1) 0.511 MHz 1.023 MHz P-code(L1,L2) 5.110 MHZ 10.23 MHz

  9. The GPS Space Segment • 24 Satellites, 3 active spares • 6 Orbital planes inclined at 55 degrees • 1 orbit = 11 hours 58 min. • 20,200 kilometers height The GLONASS Space Segment • 24 Satellites, 3 active spares • 3 Orbital planes inclined at 64.8 degrees • 1 orbit = 11 hours 15 min. • 19,100 kilometers height

  10. GNSS Comparison

  11. All the satellite signals are received GALILEO GLONASS GPS L1 L2 CA L1 L2 L1CA L1P L2P L1P L2P L2C L2CA L5 E2-L1-E1 E5 E6

  12. GALILEO GLONASS GPS Increasing satellites of number 30 78 24 24

  13. GPS Components • Space Segment Constellations of satellites. • Control Segment Monitor and control stations for tracking and managing satellites. 3. User Segment Receivers designed to receive, decode and process satellite data.

  14. System Overview Space Segment Information in one direction Bi-directional Information User Segment Control Segment

  15. Control Stations COLORADO SPRINGS (MCS) HAWAII KWAJALEIN DIEGO GARCIA ASCENSION

  16. The User Segment

  17. The User Segment

  18. The User Segment

  19. Receiver Types 1. Navigation receiver Distance measured with C/A code

  20. Receiver Types 2. Geodetic or Surveying receiver

  21. Positioning SOLUTION: DX, DY, DZ Absolute Positioning (Point Positioning) SOLUTION:X,Y,Z Relative Positioning (Baselines-Vector)

  22. How Does GPS Work? GPS Receiver calculates position by one of the following methods: a) Pseudo-Range Measurements Less Accuracy

  23. Distance are measured in GPS Positioning • With codes • C/A code (300 m.) • P code (30 m.)

  24. a) Pseudo-Range Measurements Range = (Time Taken for signal to reach Receiver from Satellite) x (Speed of light = 3*108 m/s) Range Range Range Range Receiver

  25. How Does GPS Work? GPS Receiver calculates position by one of the following methods: b) Carrier-Phase Measurements More Accuracy

  26. Distance are measured in GPS Positioning • By signal carriers phase • L1 carriers (19 cm.) • L2 carriers (24 cm.)

  27. b) Carrier-Phase Measurements Range = (Whole no. of Wavelengths from Satellite to Receiver) + (Fractional Part of Wavelength) Range Range Range Range Receiver

  28. Errors in GPS Survey • Satellite - Orbit = 5 m. • - Clock = 1 m. • 2. Signal Propagation – Ionospheric (Dual freq) = cm.- dm. • - Troposheric = dm. • - Multipath = 5 m. • Receiver - Observation noise = 1-10 m. • - Hardware delay = m. • - Antenna phase center = mm.- cm.

  29. Earth History Geoid Ellipsoid After that...a Geoid (Helmert, 1884) Helmert Geoid model accounts for Deflection of the vertical

  30. Earth Surface Representation TERRAIN GEOID (MSL) ELLIPSOID • Geoid • Ocean surface free of disturbances (Helmert, 1884). • Equipotential Surface of the Earth’s Gravity Field. Ellipsoid Geometric representation of the Earth Surface.

  31. Heights H TERRAIN h N GEOID (MSL) ELLIPSOID N=h-H h= Ellipsoidal height H= Orthometric height N = Geoid Undulation • How EGM works ? • EGM96 • EGM2008

  32. Orthometric Heights

  33. Coordinate System j l Normal to Ellipsoid Z(CIO) Up ECEF Coordinate System (X,Y,Z) Topocentric System (N,E,U) Geographic Coordinates (b,l,h) North East Station Y X(Greenwich Meridian)

  34. Field Methods Survey • Static Survey • Fast or Rapid Static Survey • Kinematic Survey • Real Time Kinematic (RTK) Survey • - Single base • - Network RTK (VRS, MAC, FKP)

  35. Mission Planning GPS & GLONASS GPS Only

  36. Dilution of Precision (DOP) • VDOP =standard deviation in vertical • HDOP =standard deviation in horizontal position(2D) • PDOP =standard deviation in position(3D) • TDOP =standard deviation in Time • GDOP =standard deviation in position(3D) and time (Geometrical)

  37. Dilution Of Precision (DOP) DOP = σ /σ0 σ = positioning accuracy σ0 = observation(pseudorange) accuracy Poor Geometry

  38. Good Geometry

  39. Static Survey

  40. Static GPS+ Survey

  41. Process data

  42. Fast Static

  43. The RTK Concept

  44. RTCM vs. CMR • Radio Technical Commission for Maritime Services (More than twice as long of a message format) • Compact Measurement Record

  45. VRS Network

  46. VRS Network

  47. VRS Network

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