Knowing where you are and where

1. Knowing where you are and where other things are anytime, anyplace!

2. The National Spatial Reference System (NSRS) is a consistent national coordinate system that specifies latitude, longitude, height, scale, gravity, and orientation throughout the Nation, as well as how these values change with time. National Spatial Reference System

3. 0.02 Meter - Horizontal 0.04 Meter - Ellipsoid Height CORS 1994 - Imporving Positional Accuracy REFERENCE TIME NETWORK LOCAL FRAME SPAN ACCURACY ACCURACY NAD 27 1927-1986 10 Meters First-Order (1 part in 0.1 million) NAD 83 1986-1990 1 Meter First-Order (1 part in 0.1 million) HARN 1987-1997 0.1 Meter B-Order (1 part in 1 million) A-Order (1 part in 10 million)

5. Continuously Operating Reference Stations

6. CORS Advantages • 3-dimensional (Lat., Long., & Ellipsoid Ht. or X, Y, & Z) • Eliminates control points reconnaissance (time and money). • Eliminates needing people and equipment at a control points. • Direct tie to National Spatial Reference System (NSRS). • CORS positions and velocities are available in both NAD 83 and ITRF coordinate systems. • CORS positions are of the highest accuracy. • CORS positions are continuously monitored and will be updated if the site moves.

7. CORS Data Quality

8. U.S. Coast Guard Sites • 20% of National CORS (80 of 400) • 27% of UFCORS Requests (15,400 of 56,994 in July) • 52 Sites With Met Sensors • Highly Reliable • Easy to Add New Ones • Economies of Partnership

9. CORS Data Access • Hardcopy Data Sheets • Floppy Disks • CD-ROMS • Bulletin Board Service • Internet – FTP and Web • UFCORS, CORSAGE, OPUS, Cooperative CORS • Objective - Easier, Cheaper, Faster Access

10. UFCORS • “User Friendly” CORS • Value-added Service • Removes Underlying Complexity • Customized Data Product

11. NGS Home Page www.ngs.noaa.gov

13. UFCORS Page

16. CORSAGE • CORSAGE - CORS Amiable Geographic Environment • Meta-data – Data about data. • Address – www.ngs.noaa.gov/CORS

19. Coordinates (positions & velocities) Data availability profiles (charts showing times for which data has been collected) Data sheets (descriptive information) Log files (descriptive information) RINEX Data (observation files) Time series of positional coordinates CORSAGE Meta-data

20. OPUS • On-line Positioning User Service • Provide GPS users faster & easier access to the National Spatial Reference System (NSRS)

22. How Does OPUS Work? • Submit RINEX file through NGS web page • Processed automatically with NGS computers & software • With respect to 3 suitable National CORS • Solution via email (usually in minutes)

23. OPUS Web Page

24. OPUS - Select Reference Site(s)

25. OPUS Guidelines • Must submit dual-frequency (L1/L2) data • Must submit at least 2 hrs of data • No kinematic/Rapid Static • No Glonass • Correct vertical requires: • antenna type • antenna height

26. OPUS – Computing Positions • NGS PAGES software • Ionosphere free • Tropospheric scale height adjusted • Fixed ambiguities • Average solution to 3 suitable CORS • ITRF and NAD83 positions returned

27. OPUS Output

28. Cooperative CORS • The Data are Located on the Participant’s Server • Accessible via a Link on the NGS CORS Web Site • Position is Computed with NGS Software • Position is Sanctioned by NGS to be consistent with the NSRS

34. UFCORS Usage Statistics

35. OPUS Usage Statistics

36. Future Directions • UFCORS • Web Service – “Computer Friendly CORS” • CORSAGE • GSAC Meta data. • OPUS • Better treatment of RINEX-2 header errors is being implemented. Some translators are not compliant with the RINEX-2 standard. • Single frequency data processing is being considered.

37. QUESTIONS? http://www.ngs.noaa.gov/OPUS/ opus@ngs.noaa.gov