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National CORS: Products & Services

National CORS: Products & Services. Richard Snay NOAA’s National Geodetic Survey Civil GPS Service Interface Committee San Juan, Puerto Rico May 23, 2006. Continuously Operating Reference Stations (CORS). Current CORS Coverage in Puerto Rico. CORS ANTENNAS. CORS SITES.

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National CORS: Products & Services

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  1. National CORS: Products & Services Richard Snay NOAA’s National Geodetic Survey Civil GPS Service Interface Committee San Juan, Puerto Rico May 23, 2006

  2. Continuously Operating Reference Stations (CORS)

  3. Current CORS Coverage in Puerto Rico

  4. CORS ANTENNAS CORS SITES

  5. Mexican National Active Geodetic Network

  6. CORS OVERVIEW • CORS Network contains 920+ sites • CORS Network growing at rate of 15 sites per month • More than 175 organizations participate in the CORS program • Provides code range (C/A, P1, P2) • and carrier phase observations (L1, L2) • Expect to provide L2C code range in near future

  7. CORS APPLICATIONS • Postmission Static Positioning (cm-level accuracy with a few hours of data, dm-level accuracy with one minute of data) • Postmission Kinematic Positioning (dm-level accuracy for an aircraft, boat, or land vehicle) • Geophysics / Crustal Motion • Meteorology / Water Vapor in Atmosphere • Space Weather / Free Electrons in Ionosphere

  8. Positioning Error vs. Duration of the Observing Session Dual-frequency GPS carrier-phase observations

  9. Positioning Accuracy with Code Data Observation Time = 1 minute red = east-west blue = north-south RMS error = 25 cm + 2 ppm

  10. Hourly Forecast of Precipitable Water

  11. Three ways to download CORS Information • Web-based User-Friendly CORS (UFCORS) • Web-based “Standard” download • FTP (File Transfer Protocol)

  12. OPUS Online Positioning User Service http://www.ngs.noaa.gov/OPUS/ opus@ngs.noaa.gov

  13. Collect at least 2 hours of GPS (dual frequency carrier phase) data • Submit your GPS data file(s) through NGS web page HOW DOES OPUS WORK? • Your data will be processed automatically, together with GPS data from 3 suitable CORS, using NGS computers and software • Receive computed positional coordinates via email (usually in minutes)

  14. ARP The height is measured vertically (NOT the slant height) from the mark to the ARP of the antenna. The height is measured in meters. The ARP is almost always the center of the bottom-most, permanently attached, surface of the antenna. See GPS Antenna Calibration for photo’s and diagrams that show where the ARP is on most antennas: http://www.ngs.noaa.gov/ANTCAL/ If the default height of 0.0000 is entered, OPUS will return the position of the ARP. MARK HOW IS THE ANTENNA HEIGHT MEASURED?

  15. How Does OPUS Compute Position? 3 separate baselines computed 3 separate positions averaged

  16. Place the Base Station over your first point and begin RTK survey ensuring that you are collecting Raw Data for at least 2 hours (This data will be sent to OPUS). We will now refer to this as OPUS1. B9999-1 B9999-2 Start Rover and begin setting and controlling your panels P4 P1 P2 P5 P3 P6

  17. Move the Base Station over your second point and begin RTK survey ensuring that you are collecting Raw Data for 2 hours. (This data will also be sent to OPUS). We will now refer to this as OPUS2. Start Rover and begin controlling your panels from the second location. P4 P1 P2 P5 B9999-1 B9999-2 P3 P6

  18. OPUS-DB (OPUS-DataBase) photo(s) description form GPS data Observation log NGS website: OPUS-DB NGS magic NGS DATABASE

  19. ONGOING CORS RESEARCH * Developing OPUS-GIS which will process a few minutes of GPS code range data (for sub-meter accuracy).

  20. ONGOING CORS RESEARCH * Developing OPUS-RS (rapid static) that will enable users to obtain positional coordinates with cm-level accuracy using only 15 minutes of GPS carrier phase data.

  21. ONGOING CORS RESEARCH • Exploring the use of NTRIP to stream GPS data from selected CORS via the Internet. • Should NOAA use NTRIP to stream ionospheric and/or tropospheric models via the Internet?

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