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The Global Positioning System for the Geosciences Summary and Proceedings of a Workshop on Improving the GPS Reference Station Infrastructure for Earth, Oceanic, and Atmospheric Science Applications (1997) / Chapter Skim
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1 Introduction
Pages 6-9

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From page 6...
... Source: The Aerospace Corporation / ~ This description of the GPS is denied from Appendix C of the National Research Council report, The Global Positioning System, A Shared National Asset Recommendation for Technical Improvements and Enhancements.
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From page 7...
... , denies unauthorized access to the P-code and also significantly improves a receiver's ability to resist locking onto mimicked GPS signals, which could provide incorrect positioning information to a GPS user. P-code availability on both the L1 and L2 carrier signals through decryption capability provides authorized users with more accurate positioning and is known as the Precise Positioning Service (PPS)
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From page 8...
... These include unintentional clock and orbital errors, errors caused by atmospheric delays, multipath errors, errors caused by receiver noise, and errors due to The Global Positioning System for the Geosciences poor satellite geometry. Many techniques and technical systems have been designed to improve the accuracy of the GPS SPS.
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From page 9...
... For example, the National Aeronautics and Space Administration (NASA) and other organizations from various nations have established the International GPS Service for Geodynamics, a network of more than 140 continuously operating reference stations, data centers, and analysis centers that collectively support geophysical and geodetic research, such as the measurement of active tectonic processes, ice sheet movements, changes in sea level, and variations in the Earth's rotation.
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Key Terms

  • carrier phase
  • gps signals
  • user equipment
  • gps receivers
  • positioning information

  • gps user
  • gps reference
  • radio signal
  • reference station
  • monitoring stations

  • decryption capability
  • reference stations
  • remote monitoring
  • presidential policy
  • carrier waves

  • gps satellites
  • positioning service
  • authorized users
  • tracking techniques
  • monitor stations

  • policy directive
  • global positioning
  • errors caused
  • carrier signals
  • remote monitor

  • precise time
  • coarse acquisition
  • incorrect positioning
  • public sector
  • equipment varies


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