NYSDOT CORS Past, Present and Future
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Transcript of NYSDOT CORS Past, Present and Future
NYSDOT CORS Past, Present and Future
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
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
Satellite Ranging
Measuring the distance from a satellite Measuring the travel time of radio signals Signal travels at the speed of light
60 milliseconds70 milliseconds
40 milliseconds
TrilaterationIdeally, the three spheres will intersect at a discrete
point. 3 seconds out
7 seconds out
5 seconds out
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
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.
Differential GPS Two receivers track the SAME signals and,
therefore, errors at the SAME time
Base
User
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
NGS CORS Network
Data Availability (OSPA)
Data Availability (SYCN)
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
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)
NYSDOT CORS
CORS on 3/30/2006
Data Availability
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
CORS Installation
CORS Hardware
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
NYDOT CORS IT Infrastructure
Network Server
Site Server
user2
Cluster Server(s) Cluster Server(s)
RTK Proxy ServerRTK Data distribuiton
18 Stations
18 Stations
Site Server
user2
Control Sites/Log Static Data Distribute Static Data
Produce Real Time Data Streams withCorrections
Real Time Network Processing
Distribute Real Time Data Streams Distributes Static Data
Log .5 sec.Static data½ hourly filesStream 1 sec. Raw Data for RTK net processing
Distribute:•1 sec hourly RINEX Static Data•Single Baseline RTCM•Nearest Site RTCM•Single Cell Network RTCM•Automatic Cell Network RTCM
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
Servers
Site server 45
Site server 24
Network server 25
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
Envisioned Web Delivery
NGS
Spider Web
NGS
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
RTK Clusters
RTK Saratoga test of Cell
Verizon Coverage
Future of NYSDOT Cors
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
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
ABGPS Antenna
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
Plotted in GIS
Fall 2005 Flights in GIS
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
Questions?