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Averaging GPS/GNSS





Beginning with TPC Desktop 2024, when you take multiple GPS/GNSS observations of a survey point, TPC can average those observations to improve the accuracy of that point's position.

GNSS Averages Sneak Peek (3:45) -  See how to average mutliple GNSS observations in TPC and improve the accuracy of those survey points.


In the example shown here, 2 observations were made for point 201, a day apart.

G761  =761

  Current Y=836622.315 X=3973572.035 Z=123.36

      AVG Y=836622.372 X=3973572.026 Z=42.43 RMS Y=0.037 X=0.038 Z=0.053 PDOP=2.60 Count=352 OBS=2


G761  =761  Date/Time=03/16/23 15:03:06

    OBS 1 Y=836622.315 X=3973572.036 Z=42.14 RMS Y=0.033 X=0.034 Z=0.047 PDOP=2.40 Count=51

     DIFF Y=0.057  X=-0.009  Z=0.29


G761  =761  Date/Time=10/24/23 11:26:21

    OBS 2 Y=836622.429 X=3973572.017 Z=42.72 RMS Y=0.041 X=0.042 Z=0.059 PDOP=2.80 Count=301

     DIFF Y=-0.057  X=0.009  Z=-0.29


The two observations are averaged to compute the position of the point, displayed as the AVG (Average).

NGS User Guidelines

In their User Guidelines, NGS says "RT positioning of important data points cannot be done reliably without some form of redundancy". They provide guidelines on how to create these redundant observations.

See NGS Guidelines for Averaging GPS/GNSS

Specifying Redundant GNSS Observations in TPC

TPC provides a number of options for specifying redundant GNSS observations.  The method you choose will depend on your equipment (data collector), work flows and personal preferences. 

See Specifying Redundant GNSS Observations

Averaging GNSS Observations

TPC includes a GNSS Averages command you can use to computed the position for any GPS/GNSS point with multiple observations.

You can reject outlying observations, generate a report of the averages and export GNSS averages to a CSV file.

See Telling TPC to Average GNSS Observations.

Averaging GNSS Observations on Import

TPC also looks for GNSS points with multiple observations when importing GNSS data. If it finds one or more imported points with multiple observations, it displays the GNSS Averages dialog, allowing you to reject any outlying observations, update existing survey points with the computed averages, report the averages or export them to a CSV file.

See Averaging GNSS Observations on Import.

Reporting GNSS Averages

From the GNSS Averages dialog, you can use the Summary button to report how averages are computed for GNSS survey points with multiple GNSS observations.

See Reporting GNSS Averages 

Exporting GNSS Averages

From the GNSS Averages dialog, you can use the Export CSV button to write a CSV file with the data used to compute average positions for GNSS survey points with multiple GNSS observations.

See Exporting GNSS Averages

Related Topics

NGS Guidelines for Averaging GNSS
Specifying Redundant GNSS Observations
Telling TPC to Average GNSS Observations
Reporting GNSS Averages
Exporting GNSS Averages
Averaging GNSS Observations on Import


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