TRU (Topcon Receiver Utility): Viewing/Loading OAFs

Configure your Topcon receiver with the latest electronic options by updating its associated OAF (Option Authorization File). 

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TRU (Topcon Receiver Utility): Viewing/Loading OAFs


  • The OAF switches of Topcon GNSS receivers control all receiver functionality.
  • The OAF includes various options which control:
    • Satellite constellations that can be tracked.
    • Enabling RTK positioning on the receiver.
    • GNSS Raw Data storage memory.
    • Enabling the Inputs/Outputs of the receiver.
  • Not all available OAF options are supported by every receiver (depends on receiver specs).
  • Receiver OAFs can be upgraded anytime to meet the specific needs of the user. 
  • To access the current OAF of the receiver, connect the receiver to TRU and select the Options icon in Receiver Managing mode. 
  • The Receiver Options screen will display all the options supported by the receiver and their status.
  • The status of a particular OAF option is displayed as either Boolean or integer values:
    • Current – current value of the OAF option.
    • Permanent – purchased OAF options that have no expiration date.
    • Leased – leased OAF options that have an expiration date associated.

Option Categories


  • Controls the satellite systems that can be used (i.e. GPS, GLONASS, BeiDou, Galileo).
  • Controls the satellite frequencies that can be used (L1, L2, L2C, L5).
  • Controls various tracking algorithms (Co-op tracking, multipath reduction, QLL, PLL). 


  • ​Controls various positioning modes available to the receiver:
    • DGNSS, RTK and Variable RTK Positioning, VISOR, HD2, Position Update rates


  • ​Controls communication interfaces (Serial, USB, Ethernet).
  • Controls timing signals (PPS, Event Marker).
  • Controls raw data storage memory.
  • Input/Output:
    • Controls Input and output of DGNSS/RTK data for different correction formats:
      • RTCM 2.x, RTCM 3.x, CMR, TPS

Machine Control:

  • ​​Controls millimeter GPS functionality.


  • Enables HiPer AG mode in the receiver. 

Region Lock:

  • Controls geofencing of the receiver, based upon the set geofence limits. This can restrict the operation of the receiver to a certain area and it will not operate outside that area.


  • Miscellaneous options including Cinderella, COCOM Limits, etc. 

Upload OAF

  • All OAF files are tied to the electronic receiver ID for every receiver (which can be viewed via the Receiver Information screen in TRU). 
  • To load a new OAF into the receiver, right click on the Receiver Options screen and select Upload OAF
  • Select the OAF file (.tpo) corresponding to the receiver ID of the GNSS receiver and click Open.
  • Select Upload the File to the Receiver to load the OAF into the receiver.
  • Once the OAF has finished loading, TRU will prompt the user to reset the receiver (power cycle) so the changes to the OAF take effect. Select Yes.
  • Reconnect the receiver to TRU and select the Options icon in Receiver Managing mode. 
  • Confirm the changes to the OAF have taken effect successfully.