Suitable Accuracy for Mobile GIS Apps on iPads –

Finally, a solution has been developed to provide mapping grade accuracy for collection of data and navigation with GPS through the iPad.   Recently, Trimble released the R1 GNSS Receiver, which is able to connect to the iPad through a Bluetooth connection.  In my opinion, this is a monumental advancement for mobile GIS through significant accuracy improvements taking accuracies from 10-30 meters to sub-meter accuracies.



After using the R1 GNSS Receiver for evaluation purposes, here are my comments:

  • Downloading the GNSS Status App from the App Store was quick and easy.
    • The GNSS Status App is concise and simplistic, providing only the information and capabilities you need.
  • Read the directions for connecting the receiver with the iPad.
    • There is only one button and two lights to work from on the receiver.
    • It took 15-30 minutes to figure out the connection process. After the initial connection process, connecting again is pretty simple.
  • Make sure to enable SBAS under the Real-time Configurations .

This improved the accuracy of the unit from approximately 9-12 feet to 2.5- 4 feet

GNSS App screen shot


  • If you have a VRS account, you can connect to that for most optimal accuracies.
  • Test the Apps to make sure the connection is working on the GIS Apps (ArcGIS Green App, ArcGIS Explorer App, ArcGIS Collector App, etc.)
    • I did this by placing the receiver on stationary object and then walked 30 feet from the receiver with the iPad.
      • Since the blue dot representing my location didn’t move, it validated that the location is being pulled from the R1 GNSS receiver.
    • After picking up the receiver, putting it on my belt, and walking the same 30 foot route, the blue dot representing my location moved with me.
  • Start collecting points and testing the GPS accuracies using the GNSS Status App.
    • My lowest accuracies (30 inches) where achieved when the R1 receiver was place on an stationary object by itself with no objects obstructing its view of the sky.
    • When the R1 receiver was clipped to my belt, accuracies were 3-4 feet.


The approximate cost for the R1 GNSS receiver is $2,500, which in my opinion is a fair price and worth the investments if you are using GIS Apps on an iPad to collect or locate infrastructure in the field daily or weekly.


More information related to the R1 GNSS receiver is located at