Dan Colbert

Tip of the Week #14 - Using the "Auto" reference frame settings in Trimble Mobile Manager

Blog Post created by Dan Colbert on Aug 6, 2020

Does your collected GNSS data not line up with your existing data properly?  Trimble Mobile Manager (TMM) has powerful features to help.  And, to help make it as easy as possible, TMM uses an “Auto” selection feature which makes educated assumptions about how to set it up for you.


This is vitally important in the case your existing data is in a reference frame (datum) which is different from that of a real-time correction source, such as VRS or Trimble RTX.  To make this happen, TMM needs to know the reference frame of any real-time source being used, AND the desired reference frame for the final output position.


This configuration is done in TMM by choosing Menu -> GNSS Configuration



The “Auto” setting can be found in two places:

  1. The GNSS source reference frame setting when configuring a custom real-time correction source

  2. The Detection mode when setting up the GNSS output reference frame 


Auto-selection of the real-time correction source reference frame

The first element of proper reference frame configuration in TMM is to setup the real-time correction source.  Select Custom local in the GNSS correction source setting, and enter the connection details.


With the GNSS source reference frame set to Auto, TMM will select the most relevant current local datum based on the device’s current location.  For example, in the Continental US, TMM will choose NAD83 (2011) Epoch 2010.0 when the GNSS source reference frame is set to Auto.


Often, it’s best to research the reference frame of the real-time source you’ll be using and manually enter those values to avoid any potential discrepancies.  However, in the absence of that information, the Auto selection will likely make the correct choice.  It's important to know that TMM doesn't have the details of your specific custom real-time source, the Auto selection is made based on the current location of the device.


Auto-selection of the GNSS output reference frame

Once the real-time correction setup is complete, finish the setup by setting the reference frame of the output position.  This is done through the GNSS Output - Detection mode.  Similar to the GNSS source reference frame configuration, setting the Detection mode to Auto will select the most current local datum based on the device’s current location.