1. Global Positioning System
    1. Space-based global radionavigation satellite system
  2. History
    1. Predecessors
      1. Ground based
        1. DECCA
        2. LORAN
        3. Omega
      2. Space based
        1. Transit (USA)
        2. Timation (USA)
        3. Tsiklon (USSR)
    2. 1973 GPS project development
    3. 1978 launch first experimental satellite
    4. 1979 Decision to expand the GPS system. Thereupon the resources are considerably shortened and the program is restructured. At first only 18 satellites should be operated. 1988 the number of satellites is again raised to 24, as the functionality is not satisfying with only 18 satellites.
    5. 1985 ten more satellites had been launched to validate the system
    6. 1993 Initial Operational Capability
    7. 1995 Full Operational Capability
    8. 2000 Selective Availability discontinued
    9. 1980 Launching of the first Block I satellite carrying sensors to detect atomic explosions.
    10. 1983 When a civilian airplane of the Korean Airline (Flight 007) was shot down after it had gone lost over Sovjet territory, it was decided to allow the civilian use of the GPS system.
    11. 1989 The first Block II satellite was installed and activated.
    12. 1990 - 1991 Temporal deactivation of the selective availability (SA) during the Gulf war. In this period civil receivers should be used as not enough military receivers were available. On July 01, 1991 SA is activated again.
    13. 08.12.1993 The Initial Operational Capability (IOC) is announced. In the same year it is also definitely decided to authorize the world wide civilian use free of charge.
    14. March 1994 The last Block II satellite completes the satellite constellation.
    15. 17.07.1995 Full Operational Capability (FOC) is announced.
    16. 01.05.2000 Final deactivation of the selective availability and therefore improvement of the accuracy for civilian users from about 100 m to 20 m.
    17. 25.09.2005 Launch of the first IIR-M GPS-satellite. This new type supports the new military M-signal and the second civil signal L2C.
    18. 28.05.2005 Lauch of the first IIF GPS-satellite. This new type supports the new L5 signal.
  3. Basic concepts
    1. Radiowaves
    2. Orbits
      1. 1 orbit takes 12 hours sidereal time
        1. Is: 11:58 hh:mm Earth time
      2. 6 planes
        1. Inclination to Equator: 55 degrees
        2. 4 slots
      3. Height of the orbits: ~ 20.200 km
      4. Speed of satellites: 3.9 km/sec
      5. Mean distance from the middle of the earth is 26560 km
    3. Triangulation
      1. Topic
    4. Accuracy
      1. Typical accuracy: ~ 15 meter
      2. Typical accuracy of dGPS: ~ 3-5 meter
      3. Typical accuracy with augmented systems: ~ 1-5 meter
    5. Differential GPS (dGPS)
    6. Assisted GPS (A-GPS)
    7. Atomic clocks
      1. Cesium
      2. Rubidium
  4. Segments
    1. Space
      1. Satellites
        1. Block I
          1. Block I
          2. Launch period 1978-1985 Successful launches: 10 Failed launches: 1
        2. Block II
          1. Block II
          2. Launch period 1989-1990 Successful launches: 9
        3. Block IIA
          1. Block IIA/IIR/II-M
          2. Launch period 1990-1997 Successful launches: 19
        4. Block IIR
          1. Launch period 1997-2004 Successful launches: 12 Failed launches: 1
        5. Block IIR-M
          1. Launch period 2005-2009 Successful launches: 8
        6. Block IIF
          1. Block IIF
          2. Launch period 2010-2011 Successful launches: 1 In preparation: 11
        7. Block IIIA
          1. Block IIIA
          2. Launch period 2014-? Planned launches: 12
        8. List of GPS satellite launches
    2. User
      1. You, I and millions more (both military and civilian)
    3. Control
      1. A Master Control Station (MCS)
      2. An alternate MCS
      3. Four dedicated ground antennas
      4. Six dedicated monitor stations
        1. Monitor station
      5. Access to other control networks
  5. Signals
    1. L1
      1. 1575.42 MHz
    2. L2
      1. 1227.60 MHz
    3. L3
      1. 1381.05 MHz
    4. L4
      1. 1379.913 MHz
    5. L5
      1. 1176.45 MHz
    6. Message format
      1. Subframe 1
        1. Satellite clock, GPS time relationship
      2. Subframe 2-3
        1. Ephemeris (precise satellite orbit)
      3. Subframe 4-5
        1. Almanac component (satellite network synopsis, error correction)
      4. Message format
  6. Error sources
    1. Ephemeris data
      1. Error: ± 2.5 meters
    2. Satellite clock
      1. Error: ± 2 meters
    3. Ionosphere
      1. Error: ± 5 meters
    4. Troposphere
      1. Error: ± 0.5 meters
    5. Mulitpath
      1. Error: ± 1 meter
    6. Receiver
      1. Error: ± 1 meter
    7. Error sources
  7. Applications
    1. Military
      1. (null)
    2. Civil
      1. Route navigation
      2. Find my ...
  8. Other systems
    1. Terrestrial systems
    2. Space-based (operational)
      1. Glonass
      2. Beidou
    3. Developmental
      1. Galileo (Europe)
      2. Compass (China)
      3. IRNSS (India)
      4. QZSS (Japan)
    4. Augmentation
      1. EGNOS
      2. GAGAN
      3. GPS-C
      4. JPALS
      5. LAAS
      6. MSAS
      7. WAAS
      8. StarFire
  9. References
    1. Status
    2. Status explained
    3. Wikipedia
  10. Author: Nico Somerwil Harderwijk, Netherlands July 2011 gps@somerwil.nl http://www.somerwil.nl/gps (Dutch)
Note