GPS: Global Positioning System

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 GPS in the late 1990s GPS in the 2000s  GPS Today 


What is GPS, and how do we use it?

GPS, or Global Positioning Service, uses a network of satellites to locate the position of someone or something on the earth's surface. Our office spearheads the County's GPS efforts to keep track of the location of utilities, like sewer and storm manholes and fire hydrants. 

The county uses Trimble R2 antennas paired with Collector for ArcGIS as well as Trimble Geo7 units and TSC2/R6 units for survey.


What makes our program special?

In 2015, Columbia County's Reference Station became a component of Trimble's VRS NowTM Network. VRS Now™ provides instant access to real-time kinematic (RTK) corrections utilizing a network of permanent (fixed) continuously operating reference stations.  It is a subscription based service from Trimble Navigation.

We operate a Trimble NetR9 CORS (Continuously Operating Reference Station) and provide data corrections via IP for GNSS data free of charge for Single-Base and through the Trimble subscription for VRS. The National Geodetic Survey (NGS), an office of NOAA's National Ocean Service, coordinates two networks of continuously operating reference stations (CORS): the National CORS network and the Cooperative CORS network. Each CORS site provides Global Positioning System (GPS) carrier phase and code range measurements in support of 3-dimensional positioning activities throughout the United States and its territories.


What is the difference between Single-Base, VRS, and CORS?

All three of these methods allow for centimeter horizontal and vertical accuracy based upon your receiver type. Some of the differences are:

  • Single-Base is a service provided at no-cost and is available for real-time corrections during data collection.
  • Trimble VRS Now™ is subscription based and allows for real-time corrections from multiple Trimble Reference stations.
  • CORS is no-cost, and is provided for differential correction after data is collected in the field.  CORS correction information includes data from the GPS constellation.


What are the options for receiving our Real-Time Corrections? 

Formats available for Single Base Real-Time Corrections:

  • CMR+
  • RTCM v. 2.3 and DGPS
  • RTCM v. 3.0

The Continuously Operating Reference Station is a Trimble NetR9 with a Zephyr GNSS Geodetic II Antenna.  This reference station collects and broadcasts one second positions from GPS and GLONASS constellations.   This functionality improves efficiency and accuracy of data collection and survey applications. Open the Trimble data sheet.

Data is also available for download from the National Geodetic Survey's Columbia County CORS site.  


Who do I contact about this service?

Please email our department any questions you may have about the reference station. You can submit the request for data access form as well.

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