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WAAS Sites Enable Kinematic GPSers to Soar with CORS 09.23.2002

September 23, 2002
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Four WAAS sites became operational as CORS in August 2002 and at least 20 additional WAAS sites will join the CORS network over the next few months.

The Federal Aviation Administration (FAA) and the National Oceanic and Atmospheric Administration (NOAA) are collaborating to incorporate the Global Positioning System (GPS) base stations of the Wide Area Augmentation System (WAAS) into the National Continuously Operating Reference Station (CORS) network. Indeed, WAAS sites located in Oakland, CA; Albuquerque, NM; and Jacksonville, FL became operational as CORS in August 2002. At least 20 additional WAAS sites will join the CORS network over the next few months.

FAA is developing WAAS to promote safe and efficient air navigation. GPS data from the WAAS sites are transmitted to data processing centers where regional "correctors" to the GPS radio signals are computed. These correctors are then transmitted to GPS users via satellite to enable real-time positioning accurate to a few meters.

NOAA, through its CORS program, will publicly distribute the WAAS GPS data--together with GPS data gathered from hundreds of other ground-based stations--free of cost via the Internet. CORS GPS data enable GPS users to position points of interest with an accuracy of a few centimeters, but not in real time. CORS data also serve to enhance weather forecasting by monitoring the distribution of water vapor in the atmosphere. CORS data are also used to monitor crustal motion.

The fact that each WAAS site records GPS radio signals each and every second will prove of great value to those CORS users involved in kinematic positioning; that is, in computing the travel path of a platform moving across the land or over the water or in the air. In the case of an aircraft remotely sensing features on Earth, for example, project specifications often require that the aircraft's position be determined with a precision of a few decimeters once per second. GPS radio signals are recorded only once every 30 seconds at most other CORS. While it may be possible to interpolate GPS data from 30 seconds to 1 second, the availability of observed 1- second data removes the chore and uncertainty associated with interpolation. Other CORS partners have also established "1-second" GPS base stations, most notably the Departments of Transportation in Vermont, Michigan, and Florida. WAAS sites, however, feature greater reliability because each site includes three independent GPS base stations to ensure continuity of operation for air navigation safety. WAAS GPS data also streams to NOAA in near real time, whereas most other CORS data arrive at NOAA either in hourly or daily packets. These three features: (1) a 1-second sampling rate, (2) triple station redundancy, and (3) near real-time- streaming input will provide CORS users with GPS data having a high sampling rate in a reliable and timely manner. These features will especially benefit those CORS users involved in kinematic positioning. By combining the Trimble interface with CAiCE's Visual Survey Software, users can now directly import and export survey data to and from the Trimble Survey Controller¿software to Visual Survey Software ensuring total compatibility of data files between the two systems. By eliminating the need to translate or convert data, Trimble and CAiCE provide surveyors and civil engineers a seamless solution to integrate data, saving time and eliminating the loss or corruption of data. The new integration capabilities allow mutual CAiCE and Trimble users to:

  • Import job data from Trimble's TSC1, TSCe or ACU controllers running the Trimble Survey Controller software, PC Card, or Geodimeter 600/Trimble Geodimeter Control Unit directly into the CAiCE database using the Trimble interface.
  • Export complete or partial road definitions (horizontal alignments, vertical alignments and cross section data) for upload to the Trimble Survey Controller software.
  • Export a CAiCE DTM surface as a triangle model to the Trimble Survey Controller software.
  • Export a CAiCE feature table as a feature code library to the Trimble Survey Controller software.
  • Create a point file for upload to the Trimble Survey Controller software or Geodimeter 600/Trimble Geodimeter Control Unit.

The Federal Aviation Administration (FAA) and the National Oceanic and Atmospheric Administration (NOAA) are collaborating to incorporate the Global Positioning System (GPS) base stations of the Wide Area Augmentation System (WAAS) into the National Continuously Operating Reference Station (CORS) network. Indeed, WAAS sites located in Oakland, CA; Albuquerque, NM; and Jacksonville, FL became operational as CORS in August 2002. At least 20 additional WAAS sites will join the CORS network over the next few months.

FAA is developing WAAS to promote safe and efficient air navigation. GPS data from the WAAS sites are transmitted to data processing centers where regional "correctors" to the GPS radio signals are computed. These correctors are then transmitted to GPS users via satellite to enable real-time positioning accurate to a few meters.

NOAA, through its CORS program, will publicly distribute the WAAS GPS data--together with GPS data gathered from hundreds of other ground-based stations--free of cost via the Internet. CORS GPS data enable GPS users to position points of interest with an accuracy of a few centimeters, but not in real time. CORS data also serve to enhance weather forecasting by monitoring the distribution of water vapor in the atmosphere. CORS data are also used to monitor crustal motion.

The fact that each WAAS site records GPS radio signals each and every second will prove of great value to those CORS users involved in kinematic positioning; that is, in computing the travel path of a platform moving across the land or over the water or in the air. In the case of an aircraft remotely sensing features on Earth, for example, project specifications often require that the aircraft's position be determined with a precision of a few decimeters once per second. GPS radio signals are recorded only once every 30 seconds at most other CORS. While it may be possible to interpolate GPS data from 30 seconds to 1 second, the availability of observed 1- second data removes the chore and uncertainty associated with interpolation. Other CORS partners have also established "1-second" GPS base stations, most notably the Departments of Transportation in Vermont, Michigan, and Florida. WAAS sites, however, feature greater reliability because each site includes three independent GPS base stations to ensure continuity of operation for air navigation safety. WAAS GPS data also streams to NOAA in near real time, whereas most other CORS data arrive at NOAA either in hourly or daily packets. These three features: (1) a 1-second sampling rate, (2) triple station redundancy, and (3) near real-time- streaming input will provide CORS users with GPS data having a high sampling rate in a reliable and timely manner. These features will especially benefit those CORS users involved in kinematic positioning.

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