For Real Time GPS corrections in the field I have posted below some Midwestern websites that will allow you to sign up for Username and Password to access the base station data Real Time.  Corrections for Trimble Mapping GPS hardware in a VRS/RTN environment can obtain Submeter, Sub Foot (Decimeter) and Centimeter accuracy depending on the model of GPS receiver and software you are using.

Trimble and Seiler Instrument support the following Mapping Grade devices on a VRS/RTN: 

What is a Realtime GPS Network and how does it work? (credit to USGS)

For the FREE VRS and RTN’s go to one of the following websites below to sign up for a User Name and Password by filling out the “User Agreement”.

For the paid for VRS networks please contact your sales rep for the Seiler Midwest RTK in Nebraska and for the Trimble VRS NOW (requires login) network in Illinois.  See also the links below under the title “FEE based VRS/RTN’s”.

Check with me if you have further questions as not all *VRS and *RTN’s are free:  [email protected]

  • You will need a data plan package for your cell phone, sim card or MiFI pod.  Stick with simple phones bluetooth phone/packages or Droids with WiFI HotSpot and or MiFI’s.  The iPphone 4 with the WiFI option will work  – no other iPhones will work (only AT&T and T-Mobile Sim cards are supported in the Geo 6000 Series).
  • Most cell providers will charge more than your standard data plan that you use for texting and surfing the web on your phone as you are actually “TETHERING” your phone to your GPS unit to then dial into a Base Station Sever Network.
  • The major cell providers have been used by our staff and customers such as: Verizon, AT&T, T-Mobile, Sprint and US Cellular.  Be sure to check with any cell provider their DATA MAP before starting a project and purchasing a phone, sim card or MiFI.  Data coverages are not as widely up and running as are voice coverages by cell providers.

*VRS = Virtual Reference Stations – Trimble base stations.

* RTN = Real Time Network – Leica/Topcon and other GPS base station providers.

Free VRS/RTN’s in Midwestern USA:

Indiana DOT RTN


Kara Company “ReIL-NET” (Chicago area – 1 free for single base)

Kentucky DOT VRS

Michigan DOT RTN

Minnesota DOT VRS

Missouri DOT VRS



Wichita, KS RTN

  • FEE based VRS/RTN’s are:

Kara Company “ReIL-Net” (Chicago area)

Seiler MWRTK/Nebraska Roads DOT VRS

Tennesse DOT RTN

Illinois is a fee based and is run by Trimble called: “VRS NOW”.  It can be purchased online per month or per yearly fee through the Trimble Store.

The Trimble VRS NOW network is in other Midwestern states including Iowa and Indiana:   VRS NOW MAP 

*A General guide and where to find a VRS/RTN in your area that I may not have mentioned in the USA (credit to USGS)

**Public RTK List via GPS World Magazine January 2014

***See our blog: Real-Time Settings in TerraSync for connecting to a VRS/RTN network:

Real-Time Settings in TerraSync VRS_RTN_2