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VRS Real-Time PDOP Settings in TerraSync
When using TerraSync in a VRS (Virtual Reference System) Real-time Correction Network here are the PDOP settings that should be used.
Uncheck Smart Settings and set the following PDOP values to:
Max PDOP: 6.0
Min SNR: 39.0
Min Elevation: 10 degrees
*You will also want to set these settings in Trimble Positions “SETUP” menu for VRS Real-time use with ArcPad.
** What is PDOP in GPS/GNSS Software? PDOP stands for “Position Dilution of Precision“.
Dilution of precision (DOP) or Geometric Dilution of Precision (GDOP) is a GPS term used in Geomatics Engineering to describe the geometric strength of Satellite configuration on GPS accuracy. When visible satellites are close together in the sky, the geometry is said to be weak and the DOP value is high; when far apart, the geometry is strong and the DOP value is low.
Thus a low DOP value represents a better GPS positional accuracy due to the wider angular separation between the satellites used to calculate a GPS unit’s position.
Step 1: Open TerraSync and select STATUS menu and select the SETUP menu.
On the SETUP screen select GNSS Settings.
Step 2: Uncheck SMART SETTINGS.
*Smart Settings are only used when Differentially Correcting the .SSF file in the Trimble office software.
Therefore this setting is not needed when using a VRS for Real-time corrections.
Step 3: Change the default PDOP settings you see below from the default to what is listed in Step 4.
Step 4: Change the PDOP Settings too:
Max PDOP: 6.0
Min SNR: 39.0
Min Elevation: 10 degrees
Step 5: Once you have changed the PDOP settings click Done.
**Please see our blog/video about GNSS Settings: PDOP, SNR and Elevation Mask for Real-Time Settings TerraSync
These GNSS/PDOP settings can be used in all versions of TerraSync for Real-Time Corrections.
TerraSync 5.40 and higher is where you will see the option to uncheck “Use Smart Settings”. Please see the TerraSync Documentation: Getting Started Guide 5.40 page 191 and Getting Started Guide 5.60/5.61 page 183.
In previous versions of TerraSync prior to version 5.40 there was the “Slider Bar” that allowed users to filter between “Productivity to Precisions”. This then edited the PDOP settings all at once per what you see done manually in this video.
Jay, based on your step 2 it sounds like I should be setting up different configuration files for my technicians to use depending on whether they are collecting data or going out to find previously collected and corrected data points. Is this a common practice?
Do the PDOP settings you recommend apply universally when VRS is enabled? How would they impact navigation when using SBAS as a backup correction method when navigating?