Joe Blecha

Tip of the Week #29 - Sources of Default Standard Errors

Blog Post created by Joe Blecha on Feb 23, 2018

Network adjustments are all about detecting, managing, and distributing errors throughout your data.  Beginning the adjustment with accurate initial estimates of your total station, leveling, and GNSS errors assists the least-squares routine in the network adjustment workflow.  Where does TBC get these initial estimates?  Read on…

In the TBC Project Settings, there is a Default Standard Errors header that, not surprisingly, contains the settings that the Network Adjustment routine uses for the initial error estimates.

The default for total station data is set from the imported file, like a *.job or *.jxl.  These settings are likely set in the field software like Trimble Access and the accuracy of the instrument should be considered to establish a proper estimate.

The default for level data is set by the Level Editor, launched when you import a *.dat from a Trimble DiNi, for example:

The default for GNSS data is the result of processing the baselines.  These results are reported at the conclusion of the processing in the Baseline Processing Report:

These default settings can be changed by selecting a different source from the drop-down menu:

The Project Settings options can be set in the corresponding sub-header.  For example, if you set the Total Station source for standard errors to Project Settings, click on the Total Station sub-header to manually set the errors to use in the adjustment.

Now, armed with the knowledge of where the Network Adjustment routine takes it initial error estimates, adjust your network confidently!

 

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