NYSDOT CORS Past, Present and Future

1. NYSDOT CORS Past, Present and Future Ron Frederiks rfrederiks@dot.state.ny.us

2. Lots of Acronyms!!!!!! • GPS – Global Positioning System • ABGPS – Airborne Global Positioning System • CORS – Continuously Operating Reference Stations • NGS – National Geodetic Survey • GIS – Geographic Information System • RTK – Real Time Kinematic Positioning versus Post Processed Positioning

3. What is GPS? • Global Positioning System • Satellite-based timing and position • 24 satellites (very high orbit) • Developed by U.S. Department of Defense • Considered a Public “Utility” • Signals available free of charge

4. Satellite Ranging • Measuring the distance from a satellite • Measuring the travel time of radio signals • Signal travels at the speed of light 40 milliseconds 70 milliseconds 60 milliseconds

5. Trilateration Ideally, the three spheres will intersect at a discrete point. 3 seconds out 5 seconds out 7 seconds out

6. Accuracy of GPS • Depends on several variables • Time spent on measurements • Design of receiver • Relative positions of satellites • Can be more than 20 meters – autonomous • Sub meter to 5 meters with differential GPS • Sub centimeter with survey products and differential GPS

7. Differential Correction • What is it? • Differential Correction is the process of correcting GPS data collected by a user, with data recorded simultaneously at a base station, in order to improve accuracy. • CORS stations serve as the base stations for differential correction • Best results achieved when distance is minimized between users receiver and the base station. • Dense network of reference stations is desirable.

8. Differential GPS • Two receivers track the SAME signals and, therefore, errors at the SAME time User Base

9. Base Stations • Before NYSDOT CORS, we had to rely on the NGS CORS network • Many gaps in the NGS CORS network • NGS CORS stations collect data at different rates • NGS CORS stations were not always reliable

10. NGS CORS Network

11. Data Availability (OSPA)

12. Data Availability (SYCN)

13. NYSDOT CORS • Conceptualized requirements in 2004 • Contract let in Spring 2005 • Installation Fall of 2005 thru February 2006 • Publishing Static Data to NGS: March 2006 • Publishing RTK Corrections Summer/Fall 2006

14. What is the NYSDOT CORS? • Initially, a Network of 36 Stations Across NYS • Intended Benefits of CORS • Primary Benefit is Publication of Static GPS Data for Positioning of Project Control • Secondary Benefit is Publication of RTK Corrections (for Terrain Data Positioning and Construction Equipment Guidance)

15. NYSDOT CORS

16. CORS on 3/30/2006

17. Data Availability

18. CORS Station Installations • GPS Receivers Installed on Secure DOT Buildings • Each Antenna Mounted on an 3” Aluminum Mast • Most Masts are Attached to Masonry Load Bearing Walls • Connected to DOT Statewide (WAN) Network • GPS Data Collection is Totally Automated • Collects & Transmits Data 24/7/365 • Automated Network Processing at MO DOT in Albany • Automated Data Backup – In Case of Network Outage • NYSDOT CORS System Will Include Leica Hardware & Software

19. CORS Installation

20. CORS Hardware

21. Central Statewide Data Management • Network Monitored & Managed by DOT Network Administrators • Stations Can be Controlled Remotely from Albany (Set collection rates – view satellites) • Alarm System is Included to Warn of Data Flow Interruptions • 24 Hour Turnaround on Hardware Repairs • UPS Backup Power Source at all Stations • Continuous Monitoring of CORS Network Integrity to Detect Movement • NGS and Leica also Monitor CORS Network Integrity

22. NYDOT CORS IT Infrastructure Control Sites/ Log Static Data Distribute Static Data Produce Real Time Data Streams with Corrections Distribute Real Time Data Streams Distributes Static Data 18 Stations • Distribute: • 1 sec hourly RINEX Static Data • Single Baseline RTCM • Nearest Site RTCM • Single Cell Network RTCM • Automatic Cell Network RTCM 18 Stations Real Time Network Processing • Distribute: • 1 sec hourly static RINEX Files to RTK Proxy Server • 1 sec hourly static RINEX for internal archive. • .5 second ½ hourly raw data files to NGS • .5 second 12 hour RINEX files to NYSDOT Photogrammetry Log .5 sec. Static data ½ hourly files Stream 1 sec. Raw Data for RTK net processing

23. Servers Site server 24 Network server 25 Site server 45

24. Publication of Static GPS Data • Automated Publishing of Static Data Files to National Geodetic Survey (NGS) • Static Data Files will be Available to Public from NGS – via CORS Website • Static Data will be Published by NGS in RINEX Format • RINEX Format can be Used by Most GPS Processing Software • NGS Adjusts National Network, Publishes Positions for Reference Stations, and Distributes Station Data For the National Spatial Reference Network • Possibly (in the Future) Incorporate 5 New CORS Stations Being Installed by NY City

25. Envisioned Web Delivery NGS NGS Spider Web

26. Publication of Real Time Kinematic (RTK) Corrections • Automated Publishing of RTK Correction via Internet IP Address • RTK Corrections can Either be Solved by a Single Baseline from a CORS Station, or by a Modeled Network Solution From a Group of CORS Stations • RTK Corrections will be Streamed Out Thru an IP Address on the Web (User determined data format) • User Accounts Will be Necessary to Access RTK Corrections • DOT Will Not Charge $ For User Accounts or for Data • Data Can be Accessed by Wireless Phone with Internet Data Service Plan from a Wireless Provider • Unlimited Number of Users Can Access Data

27. RTK Clusters

28. RTK Saratoga test of Cell

29. Verizon Coverage

30. Future of NYSDOT Cors

31. NYSDOT CORS Mission • Ensure Accuracy By: • Network Positions Monitored by NGS & by DOT CORS Software • Station Positions Processed Against National Spatial Reference Network • Station Positions Reliant on Continuous Network Monitoring, not Single Station Coordinate • Ensure Reliability By: • Data Interruptions or Station Movements Linked to DOT Alarm System • 24 Hr Contracted Maintenance and Hardware Repair • Data Backups Eliminates Data Loss if System Should Go Down • Single Point of Contact and Control of Data Collection Settings • Provide Ease-Of-Use By: • Standardized Non-Proprietary Data Formats • Universally Usable With Most Major Manufacturers • Easily Accessible RTK Data Via Internet • No User Cost Charges for Data • RTK Usable Anywhere Wireless Access is Available

32. Sample ABGPS CORS Project • Block of photographs near Watertown • ABGPS data used for QA/QC of the aerial photos • ABGPS data used in Aerotriangulation adjustment to reduce the amount of ground control

33. ABGPS Antenna

34. Obtaining XYZ Coordinates • ABGPS data post-processed using a base station near the project area • Used NYSDOT CORS station in Watertown (NYWT) • Processed with GrafNav software • Specifically designed for differential correction of ABGPS data

38. Plotted in GIS

39. Fall 2005 Flights in GIS

40. In Conclusion • NYSDOT Currently has 36 CORS stations • NYSDOT is planning to expand • NYSDOT working with NGS to make NY CORS part of the National CORS • Data will be made available at no cost • Data will be delivered through web (non RTK) and registered users (RTK only) • Data delivery to be easy, accurate and reliable

41. Questions?