Gps Niladri


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A presentation based on the fundamentals of GPS

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  • Signal chosen because: The complex pattern ensures that the receiver does not accidentally synchronize up to some other signal or so the receiver won’t accidentally pick up another satellite’s signal
  • Working principal
  • Or more usually, waypoints may be entered directly by taking a reading with the unit at the location itself, giving it a name, and then saving the point.
  • drawbacks
  • PDOP = Positional Dilution of Precision
  • GPS uses Latitudes and Longitudes to reference locations.
  • Gps Niladri

    1. 1. Introduction 1.Koustav bhandari 2.Saswata ghosh 3.Abir pramanik 4.Niladri sekhar dutta 5.Subhra sankha dey Guided by saikat bose
    2. 2. What is GPS? <ul><li>GPS, which stands for Global Positioning System, is the only system today able to show you your exact position on the Earth anytime, in any weather, anywhere. </li></ul><ul><li>The three parts of GPS are: </li></ul><ul><li>GPS Satellites </li></ul><ul><li>GPS Signals </li></ul><ul><li>GPS Receivers </li></ul>
    3. 3. Satellites <ul><li>There are quite a number of satellites out there in space. They are used for a wide range of purposes: satellite TV, cellular phones, military purposes and etc. Satellites can also be used by GPS receivers. </li></ul>
    4. 4. GPS Satellites <ul><li>There are currently 24 satellites in orbit operated by the US Department of Defense that provide worldwide coverage 24 hours a day, 7 days a week, in all weather. </li></ul>                                                                                                                                 
    5. 5. Satellite System <ul><li>The 24 satellites are orbiting the earth about 12,000 miles above us . </li></ul><ul><li>They are constantly moving & making 2 complete orbits in less than 24 hours . </li></ul><ul><li>55 degrees inclination </li></ul><ul><li>The travelling speed is 7000 miles per an hour roughly . </li></ul><ul><li>The satellites are powered by solar energy & they have back-up batteries . </li></ul>
    6. 6. Some facts about satellites <ul><li>The first GPS satellite was lauched in 1978 </li></ul><ul><li>A full constellation of 24 satellites was achieved in 1994. </li></ul><ul><li>Each satellite is built to last about 10 years. </li></ul><ul><li>A GPS satellite weighs approximately 2,000 pounds and is about 17 feet across with the solar panels extended. </li></ul><ul><li>Transmitter power is only 50 watts or less. </li></ul><ul><li>GPS satellites emit continuous navigation signal </li></ul>
    7. 7. GPS Signals <ul><li>Each GPS satellite transmits data that indicates its location and the current time. All GPS satellites synchronize operations so that these repeating signals are transmitted at the same instant. </li></ul>Physically the signal is just a complicated digital code, or in other words, a complicated sequence of “on” and “off” pulses.
    8. 8. GPS Signals Properties <ul><li>Civilian GPS uses the L1 frequency of 1575.42 MHz in the UHF band . </li></ul><ul><li>The signals travel by line of sight . </li></ul><ul><li>A GPS signal contains three different bits of information . </li></ul><ul><ul><ul><li>A pseudorandom code </li></ul></ul></ul><ul><ul><ul><li>Ephemeris data </li></ul></ul></ul><ul><ul><ul><li>Almanac data </li></ul></ul></ul>
    9. 9. GPS signals errors <ul><li>Ionosphere and troposphere delays </li></ul><ul><li>Signal multipath </li></ul><ul><li>Receiver clock errors </li></ul><ul><li>Orbital errors </li></ul><ul><li>Number of satellites visible </li></ul><ul><li>Satellite geometry/shading  </li></ul><ul><li>Intentional degradation of the satellite signal </li></ul>
    10. 10. Receivers <ul><li>GPS receivers are made to communicate with GPS satellites to find out exactly where they are on the global scale of things. </li></ul>
    11. 11. Various types of Receivers <ul><li>cars </li></ul><ul><li>mobile </li></ul><ul><li>pad </li></ul><ul><li>watch </li></ul>
    12. 12. Time Difference <ul><li>The GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. </li></ul>
    13. 13. Calculating Distance <ul><li>Velocity x Time = Distance </li></ul>Radio waves travel at the speed of light, roughly 186,000 miles per second (mps) If it took 0.06 seconds to receive a signal transmitted by a satellite floating directly overhead, use this formula to find your distance from the satellite. 186,000 mps x 0.06 seconds = 11,160 miles
    14. 14. Tracking <ul><li>It is the process of monitoring object when it moves along </li></ul>
    15. 15. DGPS <ul><li>Differential GPS uses position corrections to attain greater accuracy by the use of a reference station. </li></ul><ul><li>When a station knows what it's precise location is it can compare that position with the signals from the GPS satellites </li></ul>
    16. 16. Step 123
    17. 17. 100 meter resolution
    18. 18. 30 meter resolution
    19. 19. 5 meter resolution
    20. 20. Waypoints <ul><li>Waypoints are locations or landmarks that can be stored in your GPS. </li></ul><ul><li>Waypoints may be defined and stored in the unit manually by inputting latitude and longitude from a map or other reference. </li></ul>Latitude and Longitude Your location Direction of waypoint Date and Time Waypoint
    21. 21. Data Dictionary <ul><li>GPS units collect data in: </li></ul><ul><ul><li>Points </li></ul></ul><ul><ul><li>Lines </li></ul></ul><ul><ul><li>Areas </li></ul></ul><ul><li>These are called features. </li></ul><ul><li>A data dictionary is a means by which we collect specific information about a data feature. </li></ul>
    22. 22. Shortcomings <ul><li>Line of Sight Transmissions </li></ul><ul><li>Signal Refraction </li></ul><ul><li>Signal Interference </li></ul><ul><li>Satellite Distribution </li></ul>
    23. 23. Line of Sight Transmissions <ul><li>Line of sight is the ability to draw a straight line between two objects without any other objects getting in the way. GPS transmission are line-of-sight transmissions. </li></ul>Obstructions such as trees, buildings, or natural formations may prevent clear line of sight.
    24. 24. Light Refraction <ul><li>Sometimes the GPS signal from the satellite doesn’t follow a straight line. </li></ul><ul><li>Refraction is the bending of light as it travels through one media to another. </li></ul>
    25. 25. Signal Refraction <ul><li>Signals from satellites can be like light. When they hit some interference (air patterns in the atmosphere, uneven geography, etc.) they sometimes bend a little. </li></ul>
    26. 26. Signal Interference <ul><li>Sometimes the signals bounce off things before they hit the receivers. </li></ul>
    27. 27. Satellite Distribution <ul><li>When the satellites are all in the same part of the sky, readings will be less accurate. </li></ul>
    28. 28. Applications <ul><li>Agriculture </li></ul><ul><li>Aviation </li></ul><ul><li>Marine </li></ul><ul><li>Rail </li></ul><ul><li>Road & Highway </li></ul><ul><li>Public safety </li></ul><ul><li>Space </li></ul><ul><li>Surveying & mapping </li></ul><ul><li>Timing </li></ul><ul><li>Recreation </li></ul><ul><li>Environment </li></ul>
    29. 29. Agriculture <ul><li>Farm planning </li></ul><ul><li>Field mapping </li></ul><ul><li>Soil sampling </li></ul><ul><li>Tractor guidance </li></ul><ul><li>Crops scouting </li></ul>
    30. 30. Aviation <ul><li>determination for all phases of flight from departure, en route, and arrival </li></ul><ul><li>New and more efficient air routes made possible by GPS </li></ul>
    31. 31. Marine <ul><li>Search & rescue </li></ul><ul><li>Accurate method to navigate </li></ul><ul><li>Measuring speed </li></ul><ul><li>Determine the location </li></ul>
    32. 32. Rail <ul><li>Improves safety & security </li></ul><ul><li>Helps to reduce accidents , delays, operating cost </li></ul><ul><li>Real time position information </li></ul>
    33. 33. Latitude and Longitude <ul><li>Latitude and Longitude are spherical coordinates on the surface of the earth. </li></ul><ul><li>Latitude is measured North or South of the Equator. </li></ul><ul><li>Longitude is measured East or West of Greenwich </li></ul>
    34. 34. Thanks you!