2 GPS concepts   By Mahmoud El Mewafi Mmewafi1@ excite.com Professor of Surveying and Geodesy, Public Works Dept., Faculty...
Current Satellite Navigation Systems <ul><li>1- Global Positioning System (GPS) </li></ul><ul><li>–  USA </li></ul><ul><li...
Future Satellite Navigation Systems <ul><li>•  Galileo </li></ul><ul><li>–  European Union </li></ul><ul><li>–  New servic...
GPS  (Global Positioning System)
Three Segments of the GPS Control Segment Space Segment User Segment Monitor Stations Ground Antennas Master Station
Control Segment Kwajalein Atoll US Space Command Hawaii Ascension Is. Diego Garcia Cape Canaveral Ground Antenna Master Co...
Satellites  (space segment) <ul><li>24 NAVSTAR satellites (21 operational and 3 spares) </li></ul><ul><ul><li>orbit the Ea...
Space Segment of GPS <ul><li>GPS satellites are the space segment of the system. These are space vehicles and are responsi...
GPS – User Segment (Receivers) <ul><li>Ground-based devices read and interpret the radio signals from several of the NAVST...
GPS – User Segment (Receivers)
<ul><li>Satellites have accurate  atomic clocks  and all 24 satellites are transmitting the same time signal at the same t...
Position is Based on Time T + 3 Distance between satellite and receiver = “3 times the speed of light” T Signal leaves sat...
GPS theory
XYZT
Signal From One Satellite The receiver is somewhere on this sphere.
Signals From Two Satellites
Signals From Two Satellites X? 5 Sec 3 Sec
Three Satellites (2D Positioning)
2D-3 Satellites 5 Sec 3 Sec X 4 Sec
Three Dimensional (3D) Positioning
GPS theory <ul><li>That's right, if three perfect measurements  can locate a point in  3-dimensional space,  then four imp...
GPS signal structure   <ul><li>L1 Band Frequency = 154 x 10.23 MHz = 1575.42 MHz </li></ul><ul><li>–  C/A Code at 1.024Mhz...
Characteristics of GPS Signal <ul><li>•  C/A (Coarse Acquisition) Code </li></ul><ul><li>–  Also called PRN (Pseudo Random...
Generation of L1 Band Signal
Error Sources <ul><li>•  Satellite Clock Error </li></ul><ul><li>•  Ephemeris Error </li></ul><ul><li>–  Satellite Orbit a...
Sources of GPS Error <ul><li>Standard Positioning Service (SPS ): Civilian Users </li></ul><ul><li>Source Amount of Error ...
Atmospheric Delays   <ul><li>As a GPS signal passes through the charged particles of the  ionosphere  and then through the...
Multipath   Sources of Signal Interference Earth’s Atmosphere Solid Structures Metal Electro-magnetic Fields
Receiver Errors are Cumulative! User error = +- 1 km System and other flaws = < 9 meters
DOP is the Geometric Orientation of Satellites with respect to the Antenna
GPS Satellite Geometry <ul><li>Satellite geometry can affect the quality of GPS signals and accuracy of receiver trilatera...
Ideal Satellite Geometry N S W E
Good Satellite Geometry
Good Satellite Geometry
Poor  Satellite Geometry N S W E
Poor Satellite Geometry
Poor Satellite Geometry
GPS Navigation: On the Ground Active GOTO Waypoint Location Where GOTO Was Executed Bearing =  Course Over Ground (COG) = ...
Position Fix <ul><li>A position is based on real-time satellite tracking. </li></ul><ul><li>It’s defined by a set of coord...
Waypoint <ul><li>A waypoint is based on coordinates entered into a GPS receiver’s memory. </li></ul><ul><li>It can be eith...
Planning a Navigation Route Start = Waypoint
How A Receiver Sees Your Route
GPS Waypoint Circle of Error X
GPS Survey Observation <ul><li>•  Static Observation </li></ul><ul><li>–  Antenna is fixed at a point </li></ul><ul><li>– ...
Single GPS Survey Observation <ul><li>•  Static Observation </li></ul><ul><li>–  Antenna is fixed at a point </li></ul><ul...
Differential GPS (DGPS) Survey Observation <ul><li>•  At least one base station and one rover is necessary </li></ul><ul><...
GPS - Differential Correction <ul><li>GPS error when using differential correction:  1 – 3 meters </li></ul><ul><li>There ...
Real Time Differential GPS True coordinates =  x +0,  y +0  Correction =  x -5,  y +3 DGPS correction =  x +(30-5) and  y ...
Differential Correction 2 10m 10m Base Station (w/known coordinates) Receiver (unknown Location) GPS Receiver Estimated Lo...
Differential GPS (DGPS) <ul><li>•  Base Station </li></ul><ul><li>–  Base Station is </li></ul><ul><li>located at a known ...
Rover Station <ul><li>•  Rover or Field Station </li></ul><ul><li>–  Field unit observes  </li></ul><ul><li>GPS data </li>...
Advantage of GPS surveys <ul><li>•  Three Dimensional  </li></ul><ul><li>•  Site Intervisibility Not Needed  </li></ul><ul...
<ul><li>12. What is the fastest initialization method ?  </li></ul><ul><li>13. How much data is collected at each point in...
Wide Area Augmentation System Geostationary WAAS satellites GPS Constellation WAAS Control Station (West Coast) Local Area...
How good is WAAS? With Selective Availability set to zero, and under ideal conditions, a GPS receiver without WAAS can ach...
QUESTIONS <ul><li>1. What are the advantages of GPS surveying over conventional surveying methods ? </li></ul><ul><li>2. W...
The End
GPS Applications <ul><li>Generating mapped data for GIS databases  </li></ul><ul><ul><li>“ traditional” GIS analysts & dat...
Validation <ul><li>Accuracy </li></ul><ul><li>Turnaround time </li></ul><ul><li>Cost </li></ul><ul><li>Client response </l...
GPS Applications <ul><li>Generating mapped data for GIS databases  </li></ul><ul><ul><li>“ traditional” GIS analysts & dat...
Computers In Law Enforcement <ul><li>Officers today usually have a laptop available in their vehicles with wireless Intern...
Challenges and Problems <ul><ul><li>“ We can have more data available than ever;   how can we use it effectively for law e...
ALPR Mobile Vehicle Solution <ul><ul><li>Up to two exterior cameras, mounted on roof or light bar </li></ul></ul><ul><ul><...
Applications – Amber Alert Tracking <ul><li>Application </li></ul><ul><ul><li>Mobile unit equipped with a single camera.  ...
Case Study Pennsylvania State Police Pilot -  Background <ul><ul><li>Profile </li></ul></ul><ul><ul><ul><li>Pennsylvania S...
Case Study Pennsylvania State Police Pilot -  Results <ul><li>Immediate Results </li></ul><ul><ul><li>Vehicle recovered in...
Tracking Evidence <ul><li>Police may enter documentation about evidence into a handheld computer </li></ul><ul><ul><li>Wir...
Storing Criminal Records <ul><li>NCIC (National Crime Information Center) </li></ul><ul><ul><li>FBI database of criminal j...
Online Criminal Database
Enforcing Traffic Laws <ul><li>Red-light systems use computer technology to catch drivers who run red lights </li></ul><ul...
Tracking Stolen Vehicles <ul><li>LoJack is a stolen vehicle recovery system </li></ul><ul><ul><li>A wireless radio-frequen...
Finding Missing Children <ul><li>Amber Alert system </li></ul><ul><ul><li>Immediately notifies public for help in recoveri...
 
Providing Wireless 911 <ul><li>Enhanced 911 (E-911) displays phone number and address information on operator’s computer <...
VeriChip <ul><li>Implantable microchip that stores personal information </li></ul><ul><li>Useful for tracking people with ...
Garmin’s cheapest receivers Garmin’s iQue 3600 PDA: http://www.garmin.com/products/iQue3600/ Garmin’s Forerunner 201: A wa...
Garmin GPSmap60-C Main Screens Time & Date
Garmin GPSmap60-C Satellite Page Location Satellite Strength Accuracy Estimate Skyplot
Garmin GPSmap60-C Mark Waypoint Name Symbol Average
Garmin GPSmap60-C Main Screens Setup By default, the GPSmap60 will record a Track (line feature)  whenever the unit is tur...
Bluetooth GPS Receivers Teletype’s Mini-bluetooth GPS receiver ($175) http://www.mightygps.com/Manufacturer/minibluetooth....
HP’s Ipaqs and other PDAs with GPS software Hewlett-Packard’s new iPAQ h1945 PDA Now comes equipped with a hp GPS receiver...
The End
GPS – Ellipsoid - Datum GPS uses the WGS84 (World Geodetic System of 1984) as mathematical surface (model) of the earth El...
Navigation Review <ul><li>Position on the earth is measured in terms of  latitude  and  longitude </li></ul><ul><li>Parall...
Navigation Review <ul><li>Longitude  is defined as an angle, east or west of a reference meridian passing through Greenwic...
Lat: 40 N  Lo:  20 W  60 N 40 N 20 N 20 S 40 S 60 S Equator Prime Meridian 20 W 20 E Lat:  40  00’.00N  Lo: 020 00’.00W La...
60  04’ .20” N 149  26’.10” W o o 60 o 05’ 149  30’W o 20’
Navigation Review <ul><li>Horizontal datum  is a chart coordinate reference system </li></ul><ul><li>Nautical charts are i...
By Mahmoud El Mewafi Mmewafi1@ excite.com Professor of surveting and Geodesy, Public Works Dept., Faculty of Engineering, ...
سطوح المقارنة لكل من الكرة الأرضية ونظام الجي بي اس وعملية تحويل القياسات بينهما   Sat. 2 Receiver X Z Y (0, 0, 0) WGS-84 ...
Datum Transformations   <ul><li>A number of different procedures are available for performing coordinate transformations  ...
Helmert Transformations <ul><li>The most general method of transforming coordinates from one geodetic datum to another use...
<ul><li>the geodetic coordinates ( Φ ,  λ , h) of a point it is first necessary to convert these to Cartesian coordinates,...
The End
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  • Lo 180 is approximately the International Date Line. Except where it is drawn to exclude or include bodies of land. It is drawn west of Alaska so all of Alaska has the same calendar date
  • Gps

    1. 1. 2 GPS concepts By Mahmoud El Mewafi Mmewafi1@ excite.com Professor of Surveying and Geodesy, Public Works Dept., Faculty of Engineering, Mansoura University, Egypt. Tel 002 0127440767
    2. 2. Current Satellite Navigation Systems <ul><li>1- Global Positioning System (GPS) </li></ul><ul><li>– USA </li></ul><ul><li>First Experimental Launch Feb, 1978 </li></ul><ul><li>First Operational Launch 1989 and </li></ul><ul><li>Operational Capability in Feb, 1993 </li></ul><ul><li>2- Global Navigation Satellite System (GLONASS) </li></ul><ul><li>– Russia </li></ul>
    3. 3. Future Satellite Navigation Systems <ul><li>• Galileo </li></ul><ul><li>– European Union </li></ul><ul><li>– New services like SAR (Search and Rescue) </li></ul><ul><li>– Higher Accuracy for Civil Community </li></ul><ul><li>– Tentative Plan of Launch : 2005 – 2006 </li></ul><ul><li>– Availability of Service : 2008? </li></ul><ul><li>• QZSS( Quasi-Zenith Satellite System) </li></ul><ul><li>– Japan </li></ul><ul><li>– Basically, communication satellite but also transmit </li></ul><ul><li>GPS like signals for navigation </li></ul><ul><li>• Communication </li></ul><ul><li>• Broadcasting </li></ul><ul><li>• Navigation </li></ul>
    4. 4. GPS (Global Positioning System)
    5. 5. Three Segments of the GPS Control Segment Space Segment User Segment Monitor Stations Ground Antennas Master Station
    6. 6. Control Segment Kwajalein Atoll US Space Command Hawaii Ascension Is. Diego Garcia Cape Canaveral Ground Antenna Master Control Station Monitor Station
    7. 7. Satellites (space segment) <ul><li>24 NAVSTAR satellites (21 operational and 3 spares) </li></ul><ul><ul><li>orbit the Earth every 12 hours </li></ul></ul><ul><ul><li>~11,000 miles altitude </li></ul></ul><ul><ul><li>positioned in 6 orbital planes </li></ul></ul><ul><ul><li>orbital period/planes designed to keep 4-6 above the horizon at any time </li></ul></ul><ul><ul><li>controlled by five ground stations around the globe </li></ul></ul>
    8. 8. Space Segment of GPS <ul><li>GPS satellites are the space segment of the system. These are space vehicles and are responsible for sending radio signals from space. </li></ul><ul><li>The Space Segment of the system consists of the GPS satellites. These space vehicles (SVs) send radio signals from space. </li></ul><ul><li>The nominal GPS Operational Constellation consists of 24 satellites that orbit the earth in 12 hours. There are often more than 24 operational satellites as new ones launched to replace older satellites. </li></ul>
    9. 9. GPS – User Segment (Receivers) <ul><li>Ground-based devices read and interpret the radio signals from several of the NAVSTAR satellites at once </li></ul><ul><li>Determine their position using the time it takes signals from the satellites to reach the hand-held unit </li></ul><ul><li>Calculations result in varying degrees of accuracy that depend on: </li></ul><ul><ul><li>quality of the receiver </li></ul></ul><ul><ul><li>user operation of the receiver </li></ul></ul><ul><ul><li>local & atmospheric conditions </li></ul></ul><ul><ul><li>current status of system </li></ul></ul>
    10. 10. GPS – User Segment (Receivers)
    11. 11. <ul><li>Satellites have accurate atomic clocks and all 24 satellites are transmitting the same time signal at the same time </li></ul><ul><li>The satellite signals contains information that includes </li></ul><ul><ul><li>Satellite number </li></ul></ul><ul><ul><li>Time of transmission </li></ul></ul><ul><li>Receivers use an almanac that includes </li></ul><ul><ul><li>The position of all satellites every second </li></ul></ul><ul><ul><li>This is updated monthly from control stations </li></ul></ul><ul><li>The satellite signal is received, compared with the receiver’s internal clock, and used to calculate the distance from that satellite </li></ul><ul><li>Trilateration (similar to triangulation) is used to determine location from multiple satellite signals </li></ul>How It Works
    12. 12. Position is Based on Time T + 3 Distance between satellite and receiver = “3 times the speed of light” T Signal leaves satellite at time “T” Signal is picked up by the receiver at time “T + 3”
    13. 13. GPS theory
    14. 14. XYZT
    15. 15. Signal From One Satellite The receiver is somewhere on this sphere.
    16. 16. Signals From Two Satellites
    17. 17. Signals From Two Satellites X? 5 Sec 3 Sec
    18. 18. Three Satellites (2D Positioning)
    19. 19. 2D-3 Satellites 5 Sec 3 Sec X 4 Sec
    20. 20. Three Dimensional (3D) Positioning
    21. 21. GPS theory <ul><li>That's right, if three perfect measurements can locate a point in 3-dimensional space, then four imperfect measurements can do the same thing. </li></ul><ul><li>1. (X1 - X)² + (y1 - Y)² + (z1 - Z)² = c²(t1 - T)² </li></ul><ul><li>2. (X2 - X)² + (y2 - Y)² + (z2 - Z)² = c²(t2 - T)² </li></ul><ul><li>3. (X3 - X)² + (y3 - Y)² + (z3 - Z)² = c²(t3 - T)² </li></ul><ul><li>4. (X3 - X)² + (y3 - Y)² + (z4 - Z)² = c²(t4 - T)² </li></ul>
    22. 22. GPS signal structure <ul><li>L1 Band Frequency = 154 x 10.23 MHz = 1575.42 MHz </li></ul><ul><li>– C/A Code at 1.024Mhz </li></ul><ul><li>– P Code at 10.23 Mhz </li></ul><ul><li>– Navigation Data at 50Hz </li></ul><ul><li>L2 Band Frequency = 120 x 10.23 MHz = 1227.60 MHz </li></ul><ul><li>– P Code at 10.23Mhz or </li></ul><ul><li>– Encrypted P Code called Y Code at 10.23Mhz </li></ul><ul><li>– Navigation Data Bit at 50Hz </li></ul><ul><li>Clock Frequency : 10.23MHz </li></ul>
    23. 23. Characteristics of GPS Signal <ul><li>• C/A (Coarse Acquisition) Code </li></ul><ul><li>– Also called PRN (Pseudo Random Numbers) </li></ul><ul><li>– PRN codes are unique for every satellite </li></ul><ul><li>– All the Satellites have the same frequency </li></ul><ul><li>– Modulation is done by using CDMA which is </li></ul><ul><li>a technology based on Spread Spectrum </li></ul><ul><li>– Spread Spectrum gives wider bandwidth </li></ul><ul><li>– Signal is spread and hence is below the noise floor </li></ul><ul><li>– Difficult to intercept </li></ul><ul><li>– Requires Low power </li></ul><ul><li>– Efficient use of Frequency Spectrum </li></ul><ul><li>• P Code </li></ul><ul><li>– Encrypted using Encryption Code </li></ul><ul><li>– Encrypted P code is called Y code </li></ul><ul><li>– Used basically for Military purpose </li></ul><ul><li>– Higher Accuracy </li></ul><ul><li>– Extremely difficult to intercept </li></ul><ul><li>– A very complex code </li></ul>
    24. 24. Generation of L1 Band Signal
    25. 25. Error Sources <ul><li>• Satellite Clock Error </li></ul><ul><li>• Ephemeris Error </li></ul><ul><li>– Satellite Orbit and Satellite Related </li></ul><ul><li>• Atmospheric Propagation Delay </li></ul><ul><li>– Ionospheric Delay </li></ul><ul><li>– Tropospheric Delay </li></ul><ul><li>• Receiver Noise </li></ul><ul><li>– Receiver Clock (Oscillator Noise) </li></ul><ul><li>– Thermal Noise </li></ul><ul><li>– Device Induced Interference </li></ul><ul><li>• Multipath </li></ul><ul><li>– Surrounding Environment </li></ul><ul><li>• Satellite Geometry </li></ul><ul><li>– DOPs </li></ul>
    26. 26. Sources of GPS Error <ul><li>Standard Positioning Service (SPS ): Civilian Users </li></ul><ul><li>Source Amount of Error </li></ul><ul><ul><li>Satellite clocks: 1.5 to 3.6 meters </li></ul></ul><ul><ul><li>Orbital errors: < 1 meter </li></ul></ul><ul><ul><li>Ionosphere: 5.0 to 7.0 meters </li></ul></ul><ul><ul><li>Troposphere: 0.5 to 0.7 meters </li></ul></ul><ul><ul><li>Receiver noise: 0.3 to 1.5 meters </li></ul></ul><ul><ul><li>Multipath: 0.6 to 1.2 meters </li></ul></ul><ul><ul><li>Selective Availability (see notes) </li></ul></ul><ul><ul><li>User error: Up to a kilometer or more </li></ul></ul><ul><li>Errors are cumulative and increased by PDOP. </li></ul>
    27. 27. Atmospheric Delays <ul><li>As a GPS signal passes through the charged particles of the ionosphere and then through the water vapor in the troposphere it gets slowed down a bit, and this creates the same kind of error as bad clocks. </li></ul>
    28. 28. Multipath Sources of Signal Interference Earth’s Atmosphere Solid Structures Metal Electro-magnetic Fields
    29. 29. Receiver Errors are Cumulative! User error = +- 1 km System and other flaws = < 9 meters
    30. 30. DOP is the Geometric Orientation of Satellites with respect to the Antenna
    31. 31. GPS Satellite Geometry <ul><li>Satellite geometry can affect the quality of GPS signals and accuracy of receiver trilateration. </li></ul><ul><li>Dilution of Precision (DOP) reflects each satellite’s position relative to the other satellites being accessed by a receiver. </li></ul><ul><li>There are five distinct kinds of DOP. </li></ul><ul><li>Position Dilution of Precision (PDOP) is the DOP value used most commonly in GPS to determine the quality of a receiver’s position. </li></ul><ul><li>It’s usually up to the GPS receiver to pick satellites which provide the best position triangulation. </li></ul><ul><li>Some GPS receivers allow DOP to be manipulated by the user. </li></ul>
    32. 32. Ideal Satellite Geometry N S W E
    33. 33. Good Satellite Geometry
    34. 34. Good Satellite Geometry
    35. 35. Poor Satellite Geometry N S W E
    36. 36. Poor Satellite Geometry
    37. 37. Poor Satellite Geometry
    38. 38. GPS Navigation: On the Ground Active GOTO Waypoint Location Where GOTO Was Executed Bearing = Course Over Ground (COG) = Cross Track Error (XTE) = Bearing = 65 0 COG = 5 0 XTE = 1/2 mi. Bearing = 78 0 COG = 350 0 XTE = 1/3 mi. Bearing = 40 0 COG = 104 0 XTE = 1/4 mi. Active Leg N
    39. 39. Position Fix <ul><li>A position is based on real-time satellite tracking. </li></ul><ul><li>It’s defined by a set of coordinates. </li></ul><ul><li>It has no name. </li></ul><ul><li>A position represents only an approximation of the receiver’s true location. </li></ul><ul><li>A position is not static. It changes constantly as the GPS receiver moves (or wanders due to random errors). </li></ul><ul><li>A receiver must be in 2D or 3D mode (at least 3 or 4 satellites acquired) in order to provide a position fix. </li></ul><ul><li>3D mode dramatically improves position accuracy. </li></ul>
    40. 40. Waypoint <ul><li>A waypoint is based on coordinates entered into a GPS receiver’s memory. </li></ul><ul><li>It can be either a saved position fix, or user entered coordinates. </li></ul><ul><li>It can be created for any remote point on earth. </li></ul><ul><li>It must have a receiver designated code or number, or a user supplied name. </li></ul><ul><li>Once entered and saved, a waypoint remains unchanged in the receiver’s memory until edited or deleted. </li></ul>
    41. 41. Planning a Navigation Route Start = Waypoint
    42. 42. How A Receiver Sees Your Route
    43. 43. GPS Waypoint Circle of Error X
    44. 44. GPS Survey Observation <ul><li>• Static Observation </li></ul><ul><li>– Antenna is fixed at a point </li></ul><ul><li>– Gives higher accuracy since observation is done for long time period </li></ul><ul><li>• Average of the observation cancels out some errors </li></ul><ul><li>– Only Code Phase Observation </li></ul><ul><li>– A few meters level accuracy </li></ul><ul><li>• Kinematic Observation </li></ul><ul><li>– Antenna is moving </li></ul><ul><li>– Just a few or single epoch observation at a particular point </li></ul><ul><li>– Accuracy is lower </li></ul><ul><li>– Only Code Phase Observation </li></ul><ul><li>– Sometimes error is too large, few hundreds of meters </li></ul>
    45. 45. Single GPS Survey Observation <ul><li>• Static Observation </li></ul><ul><li>– Antenna is fixed at a point </li></ul><ul><li>– Gives higher accuracy since observation is done for long time period </li></ul><ul><li>• Average of the observation cancels out some errors </li></ul><ul><li>– Only Code Phase Observation </li></ul><ul><li>– A few meters level accuracy </li></ul><ul><li>• Kinematic Observation </li></ul><ul><li>– Antenna is moving </li></ul><ul><li>– Just a few or single epoch observation at a particular point </li></ul><ul><li>– Accuracy is lower </li></ul><ul><li>– Only Code Phase Observation </li></ul><ul><li>– Sometimes error is too large, few hundreds of meters </li></ul>
    46. 46. Differential GPS (DGPS) Survey Observation <ul><li>• At least one base station and one rover is necessary </li></ul><ul><li>• Both Base station and rover logs the data at the same time or use the same time data for processing </li></ul><ul><li>• Data link must be available for real time DGPS </li></ul><ul><li>• DGPS has been widely used in many applications where accuracy is anissue </li></ul><ul><li>1- Static Observation </li></ul><ul><li>2- Kinematic Observation </li></ul>
    47. 47. GPS - Differential Correction <ul><li>GPS error when using differential correction: 1 – 3 meters </li></ul><ul><li>There are two ways that differential correction can be applied: </li></ul><ul><ul><li>Post-processing differential correction </li></ul></ul><ul><ul><ul><li>Does the error calculations after the rover has collected the points </li></ul></ul></ul><ul><ul><li>Real-time differential correction </li></ul></ul><ul><ul><ul><li>Done in real time by receiving a broadcasted correction signal (usually expensive), requiring other hardware (not just a consumer GPS receiver) </li></ul></ul></ul>
    48. 48. Real Time Differential GPS True coordinates = x +0, y +0 Correction = x -5, y +3 DGPS correction = x +(30-5) and y +(60+3) True coordinates = x +25, y +63 DGPS Site x +30, y +60 x +5, y -3 x -5, y +3 DGPS Receiver Receiver
    49. 49. Differential Correction 2 10m 10m Base Station (w/known coordinates) Receiver (unknown Location) GPS Receiver Estimated Location Differentially Corrected Estimated Position GPS Estimated Location Actual (Known) Position
    50. 50. Differential GPS (DGPS) <ul><li>• Base Station </li></ul><ul><li>– Base Station is </li></ul><ul><li>located at a known </li></ul><ul><li>Point </li></ul><ul><li>– The point is surveyed </li></ul><ul><li>by other means </li></ul><ul><li>of measurement </li></ul><ul><li>– Base Station Data </li></ul><ul><li>are broadcasted using </li></ul><ul><li>radio channel or telephone </li></ul><ul><li>line for real time DGPS </li></ul><ul><li>– Base Station Data are also recorded on </li></ul><ul><li>a PC for post processing of rover data </li></ul>
    51. 51. Rover Station <ul><li>• Rover or Field Station </li></ul><ul><li>– Field unit observes </li></ul><ul><li>GPS data </li></ul><ul><li>– For Realtime DGPS, </li></ul><ul><li>a data antenna or </li></ul><ul><li>telephone line is used </li></ul><ul><li>to receive the base </li></ul><ul><li>station log data </li></ul><ul><li>– For post processing, </li></ul><ul><li>the field data is brought </li></ul><ul><li>back to the office and post processed in the computer using Base </li></ul><ul><li>station data </li></ul>
    52. 52. Advantage of GPS surveys <ul><li>• Three Dimensional </li></ul><ul><li>• Site Intervisibility Not Needed </li></ul><ul><li>• Weather Independent </li></ul><ul><li>• Day or Night Operation • Common Reference System </li></ul><ul><li>• Rapid Data Processing with Quality Control </li></ul><ul><li>• High Precision </li></ul><ul><li>• Less Labor Intensive/Cost Effective </li></ul><ul><li>• Very Few Skilled Personnel Needed </li></ul>
    53. 53. <ul><li>12. What is the fastest initialization method ? </li></ul><ul><li>13. How much data is collected at each point in stop-and-go GPS surveying ? </li></ul><ul><li>15. What are the time limitations on re-occupation ? </li></ul><ul><li>16. Which GPS surveying method would you use for establishing control with geodetic accuracy ? </li></ul><ul><li>17. Which GPS surveying method would you use if you need to complete a job urgently </li></ul>
    54. 54. Wide Area Augmentation System Geostationary WAAS satellites GPS Constellation WAAS Control Station (West Coast) Local Area System (LAAS) WAAS Control Station (East Coast)
    55. 55. How good is WAAS? With Selective Availability set to zero, and under ideal conditions, a GPS receiver without WAAS can achieve fifteen meter accuracy most of the time.* Under ideal conditions a WAAS equipped GPS receiver can achieve three meter accuracy 95% of the time.* * Precision depends on good satellite geometry, open sky view, and no user induced errors. + - 3 meters +-15 meters
    56. 56. QUESTIONS <ul><li>1. What are the advantages of GPS surveying over conventional surveying methods ? </li></ul><ul><li>2. What is the single factor that determines whether or not a GPS survey is possible in an area and/or a project ? </li></ul><ul><li>3. What is a ‘baseline’ in GPS surveying ? </li></ul><ul><li>5. What is an ‘epoch’ in GPS terminology ? </li></ul><ul><li>6. Why is the ‘static’ GPS survey method so named ? </li></ul><ul><li>7. What is the reason for ‘minimum session length’ in static surveying ? </li></ul><ul><li>8. What factors determine the length of a session in static surveying ? </li></ul><ul><li>9. What factors determine the GPS surveying method suitable for a given area/project ? </li></ul><ul><li>10. What is the purpose of rover ‘initialization’ in kinematic surveying ? </li></ul>
    57. 57. The End
    58. 58. GPS Applications <ul><li>Generating mapped data for GIS databases </li></ul><ul><ul><li>“ traditional” GIS analysts & data developers </li></ul></ul><ul><ul><li>travel to field and capture location & attribute information cheaply (instead of surveying) </li></ul></ul><ul><li>Other uses (many in real time ): </li></ul><ul><ul><li>911/firefighter/police/ambulance dispatch </li></ul></ul><ul><ul><li>car navigation </li></ul></ul><ul><ul><li>roadside assistance </li></ul></ul><ul><ul><li>business vehicle/fleet management </li></ul></ul><ul><ul><li>mineral/resource exploration </li></ul></ul><ul><ul><li>wildlife tracking </li></ul></ul><ul><ul><li>boat navigation </li></ul></ul><ul><ul><li>Recreational </li></ul></ul><ul><ul><li>Ski patrol/medical staff location monitoring </li></ul></ul>
    59. 59. Validation <ul><li>Accuracy </li></ul><ul><li>Turnaround time </li></ul><ul><li>Cost </li></ul><ul><li>Client response </li></ul><ul><li>Developers’ response? </li></ul>
    60. 60. GPS Applications <ul><li>Generating mapped data for GIS databases </li></ul><ul><ul><li>“ traditional” GIS analysts & data developers </li></ul></ul><ul><ul><li>travel to field and capture location & attribute information cheaply (instead of surveying) </li></ul></ul><ul><li>Other uses (many in real time ): </li></ul><ul><ul><li>911/firefighter/police/ambulance dispatch </li></ul></ul><ul><ul><li>car navigation </li></ul></ul><ul><ul><li>roadside assistance </li></ul></ul><ul><ul><li>business vehicle/fleet management </li></ul></ul><ul><ul><li>mineral/resource exploration </li></ul></ul><ul><ul><li>wildlife tracking </li></ul></ul><ul><ul><li>boat navigation </li></ul></ul><ul><ul><li>Recreational </li></ul></ul><ul><ul><li>Ski patrol/medical staff location monitoring </li></ul></ul>
    61. 61. Computers In Law Enforcement <ul><li>Officers today usually have a laptop available in their vehicles with wireless Internet to </li></ul><ul><ul><li>Write tickets </li></ul></ul><ul><ul><li>Fill out accident reports </li></ul></ul><ul><ul><li>Complete routine police work </li></ul></ul><ul><ul><li>Download criminal and driving records from databases </li></ul></ul><ul><ul><li>Check license plate registrations </li></ul></ul><ul><ul><li>Retrieve information from headquarters while on the road </li></ul></ul>
    62. 62. Challenges and Problems <ul><ul><li>“ We can have more data available than ever; how can we use it effectively for law enforcement?” </li></ul></ul><ul><ul><li>“ How can we combat stolen vehicles in our community?” </li></ul></ul><ul><ul><li>“ How can our officers run more license plate checks and still do their other duties?” </li></ul></ul><ul><ul><li>“ How can we increase our officers’ safety when they’re patrolling and making traffic stops?” </li></ul></ul>
    63. 63. ALPR Mobile Vehicle Solution <ul><ul><li>Up to two exterior cameras, mounted on roof or light bar </li></ul></ul><ul><ul><li>Fixed focal length lenses for different use cases </li></ul></ul><ul><ul><li>Manual updates to database in the field </li></ul></ul><ul><ul><li>Back Office Utility software for easy data management </li></ul></ul><ul><ul><li>Global Positioning System (GPS) and Mapping Support </li></ul></ul><ul><ul><li>Integration with Mobile Video Enforcer (MVE) </li></ul></ul><ul><ul><ul><li>Alert triggers MVE recording </li></ul></ul></ul><ul><ul><li>AirMobile and MESH / 802.11 integration for wireless updates of local database </li></ul></ul><ul><ul><li>Certified for Motorola </li></ul></ul><ul><ul><ul><li>MW800 / ML900 / ML850 / Panasonic Toughbook CF-29 </li></ul></ul></ul>
    64. 64. Applications – Amber Alert Tracking <ul><li>Application </li></ul><ul><ul><li>Mobile unit equipped with a single camera. Officer can update database manually through PAGIS. </li></ul></ul><ul><li>Benefit </li></ul><ul><ul><li>Increase effectiveness of response to alerts </li></ul></ul><ul><ul><ul><li>May save lives </li></ul></ul></ul><ul><ul><ul><li>Automatic reading of licenses in the background </li></ul></ul></ul>
    65. 65. Case Study Pennsylvania State Police Pilot - Background <ul><ul><li>Profile </li></ul></ul><ul><ul><ul><li>Pennsylvania State Police are installing 1400 MW800’s Mobile Data Terminals (MDTs) </li></ul></ul></ul><ul><ul><ul><li>Colonel saw technology in Europe </li></ul></ul></ul><ul><ul><ul><li>22,000 stolen cars a year in PA </li></ul></ul></ul><ul><ul><ul><li>Customer likes trying new technology and giving feedback </li></ul></ul></ul><ul><ul><li>Pilot components </li></ul></ul><ul><ul><ul><li>6 patrol cars out of Harrisburg </li></ul></ul></ul><ul><ul><ul><li>3 shifts / 6 weeks </li></ul></ul></ul><ul><ul><ul><li>Broad “hot list” with CLEAN, NCIC, local wants and warrants </li></ul></ul></ul>
    66. 66. Case Study Pennsylvania State Police Pilot - Results <ul><li>Immediate Results </li></ul><ul><ul><li>Vehicle recovered in the first shift </li></ul></ul><ul><ul><ul><li>Sgt. Franks DeAndrea: “If we would end the test today, it would already be a full success.” </li></ul></ul></ul><ul><ul><li>Armed and dangerous suspects apprehended in the first week </li></ul></ul><ul><ul><li>Officer safety reinforced </li></ul></ul><ul><ul><ul><li>Official report: “The trooper feels the ALPR system saved his life and prevented a serious incident from occurring.” </li></ul></ul></ul><ul><ul><ul><li>Click here to view the ABC News Clip with details </li></ul></ul></ul>
    67. 67. Tracking Evidence <ul><li>Police may enter documentation about evidence into a handheld computer </li></ul><ul><ul><li>Wirelessly transmits the information to an evidence database </li></ul></ul><ul><ul><li>Prints out a bar code sticker that is placed on the physical evidence </li></ul></ul><ul><li>DNA evidence is stored in the CODIS (Combined DNA Index System) database </li></ul><ul><ul><li>Forensic and offender indexes </li></ul></ul><ul><li>Fingerprint evidence is stored in the AFIS (Integrated Automated Fingerprint Identification System) database </li></ul><ul><ul><li>Fingerprint images are scanned electronically </li></ul></ul>
    68. 68. Storing Criminal Records <ul><li>NCIC (National Crime Information Center) </li></ul><ul><ul><li>FBI database of criminal justice information </li></ul></ul><ul><ul><li>Officers check subject’s previous record after arrest </li></ul></ul><ul><li>NICS (National Instant Criminal Background Check System) </li></ul><ul><ul><li>FBI system to help gun dealers perform background checks on potential buyers </li></ul></ul><ul><ul><li>Dealer calls the Bureau of Identification to run a query on several databases </li></ul></ul>
    69. 69. Online Criminal Database
    70. 70. Enforcing Traffic Laws <ul><li>Red-light systems use computer technology to catch drivers who run red lights </li></ul><ul><ul><li>Cameras are positioned at intersection corners </li></ul></ul><ul><ul><li>A sensor loop triggers if a car moves over a certain speed </li></ul></ul><ul><ul><li>The software activates the cameras to take photos </li></ul></ul><ul><ul><li>The software then creates a record with the time, location, and the photos, and </li></ul></ul><ul><ul><li>a citation is sent to the offender </li></ul></ul><ul><li>Traffic violation fines may often be accessed and paid online </li></ul>
    71. 71. Tracking Stolen Vehicles <ul><li>LoJack is a stolen vehicle recovery system </li></ul><ul><ul><li>A wireless radio-frequency transmitter is placed in the car </li></ul></ul><ul><ul><li>The vehicle identification number of a stolen vehicle is checked against the NCIC (National Crime Information Center) </li></ul></ul><ul><ul><li>A signal can be sent to the device, which much like a GPS reports its exact location / a map can be created </li></ul></ul><ul><li>Key pass theft system </li></ul><ul><ul><li>Uses a motion sensor and uniquely coded key pass to detect unauthorized motion of a vehicle </li></ul></ul>
    72. 72. Finding Missing Children <ul><li>Amber Alert system </li></ul><ul><ul><li>Immediately notifies public for help in recovering missing children </li></ul></ul><ul><ul><li>Uses EAS (Emergency Alert System) technology </li></ul></ul><ul><ul><li>EAS broadcasts alert on radio and television </li></ul></ul><ul><ul><li>Alerts can be displayed on dynamic message signs on highways </li></ul></ul><ul><ul><li>NCMEC (National Center for Missing and Exploited Children) provides alerts via e-mail, mobile phone, pager, or AOL Instant Messenger </li></ul></ul>
    73. 74. Providing Wireless 911 <ul><li>Enhanced 911 (E-911) displays phone number and address information on operator’s computer </li></ul><ul><ul><li>The ANI (automatic number identifier) and ALI (automatic location identifier) databases provide the information </li></ul></ul><ul><li>ANI and ALI does not work with cell phones </li></ul><ul><li>FCC (Federal Communications Commission) requires that all cell phone providers equip phones with GPS (global positioning system) receivers </li></ul><ul><ul><li>GPS receiver receives signals from GPS satellite </li></ul></ul><ul><ul><li>Computer links this information to the ALI database </li></ul></ul>
    74. 75. VeriChip <ul><li>Implantable microchip that stores personal information </li></ul><ul><li>Useful for tracking people with illnesses or in danger </li></ul><ul><li>Raises privacy and legal issues </li></ul>
    75. 76. Garmin’s cheapest receivers Garmin’s iQue 3600 PDA: http://www.garmin.com/products/iQue3600/ Garmin’s Forerunner 201: A watch that uses GPS to determine current speed, average speed, exact distance traveled, etc. ( ) Basic features also available in the Forerunner 101 ($115). http://www.garmin.com/products/forerunner201/
    76. 77. Garmin GPSmap60-C Main Screens Time & Date
    77. 78. Garmin GPSmap60-C Satellite Page Location Satellite Strength Accuracy Estimate Skyplot
    78. 79. Garmin GPSmap60-C Mark Waypoint Name Symbol Average
    79. 80. Garmin GPSmap60-C Main Screens Setup By default, the GPSmap60 will record a Track (line feature) whenever the unit is turned on. Map (GoTo) Profiles
    80. 81. Bluetooth GPS Receivers Teletype’s Mini-bluetooth GPS receiver ($175) http://www.mightygps.com/Manufacturer/minibluetooth.htm Teletype’s USB GPS receiver for Laptops ($170) http://www.teletype.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=1250&Category_Code=
    81. 82. HP’s Ipaqs and other PDAs with GPS software Hewlett-Packard’s new iPAQ h1945 PDA Now comes equipped with a hp GPS receiver and navigation system ($500) http://www.shopping.hp.com/cgi-bin/hpdirect/shopping/scripts/product_detail/product_detail_view.jsp?BV_SessionID=@@@@0280349227.1102102313@@@@&BV_EngineID=ccckadddfdjlkdgcfngcfkmdflldfgg.0&landing=null&category=handhelds&subcat1=classic_performance&product_code=PF527A%23ABA&catLevel=3 Garmin’s iQue 3600 PDA: http://www.garmin.com/products/iQue3600/
    82. 83. The End
    83. 84. GPS – Ellipsoid - Datum GPS uses the WGS84 (World Geodetic System of 1984) as mathematical surface (model) of the earth Elevations are referenced to Height Above Ellipsoid (HAE)
    84. 85. Navigation Review <ul><li>Position on the earth is measured in terms of latitude and longitude </li></ul><ul><li>Parallels of latitude define position in the north-south direction </li></ul><ul><li>Latitude is measured as angle from center of earth north or south </li></ul>o o o o 70 50 30 0
    85. 86. Navigation Review <ul><li>Longitude is defined as an angle, east or west of a reference meridian passing through Greenwich, England </li></ul><ul><li>Every point on the earth has a unique address in terms of latitude and longitude </li></ul>Greenwich W E
    86. 87. Lat: 40 N Lo: 20 W 60 N 40 N 20 N 20 S 40 S 60 S Equator Prime Meridian 20 W 20 E Lat: 40 00’.00N Lo: 020 00’.00W Lat: 40 00’.00S Lo: 020 00’.00W Every place on earth has a unique location 180 Lo approx. International Date Line o o o O o o o o o o o o o o o
    87. 88. 60 04’ .20” N 149 26’.10” W o o 60 o 05’ 149 30’W o 20’
    88. 89. Navigation Review <ul><li>Horizontal datum is a chart coordinate reference system </li></ul><ul><li>Nautical charts are in the process of being standardized, not all are drawn to the same datum </li></ul><ul><li>The datum is shown on each chart </li></ul><ul><li>GPS receivers must be adjusted to the same datum as used on the chart! </li></ul>
    89. 90. By Mahmoud El Mewafi Mmewafi1@ excite.com Professor of surveting and Geodesy, Public Works Dept., Faculty of Engineering, Mansoura University, Egypt 6 Datum Transformations
    90. 91. سطوح المقارنة لكل من الكرة الأرضية ونظام الجي بي اس وعملية تحويل القياسات بينهما Sat. 2 Receiver X Z Y (0, 0, 0) WGS-84 Local Sat. 3 Sat. 1 Sat. 4
    91. 92. Datum Transformations <ul><li>A number of different procedures are available for performing coordinate transformations </li></ul><ul><li>1. Helmert T ransformation </li></ul><ul><li>2. Molodenskii T ransformation </li></ul><ul><li>3. Multiple Rregression Transformation </li></ul>
    92. 93. Helmert Transformations <ul><li>The most general method of transforming coordinates from one geodetic datum to another uses all 7 geometrical transformation parameters to convert Cartesian coordinates (X, Y and Z). The general formulation of this transformation is : </li></ul><ul><li>Where X1, Y1, Z1 Cartesian coordinates in first datum </li></ul><ul><li>X2, Y2, Z2 Cartesian coordinates in second datum. </li></ul><ul><li>The rotation angles θ x , θ y and θ z, expressed in radians in the matrix, are assumed ’small’ angles, i.e. of the order of a few seconds-of-arc </li></ul>
    93. 94. <ul><li>the geodetic coordinates ( Φ , λ , h) of a point it is first necessary to convert these to Cartesian coordinates, before the transformation can be applied. </li></ul><ul><li>Similarly, the resulting coordinates in the new datum could also be converted to the corresponding geodetic latitude and longitude using the parameters of the ellipsoid associated with this new datum. </li></ul>
    94. 95. The End
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