Navigation: Using GPS / GNSS > Averaging GPS/GNSS >

Specifying Redundant GNSS Observations

 

 

 

 

Beginning with TPC Desktop 2024, TPC provides four ways to specify redundant GNSS observations.  Each way relies on raw GNSS observations being stored with a traverse point.  See How TPC Stores GPS/GNSS Data.

GNSS Redundant Observations (9:12) - Learn how to specify multiple GNSS observations for the same survey point.


Overview

TPC provides several very flexible ways to specify matching points.

1.Point label match (default)

2.Point label contains

3.Point label difference

4.Point description contains

You select which option you want to use in the Points Match dialog.

This topic describes each of these methods.


Example

Here are two traverses representing two separate imports of GNSS data that create redundant GNSS observations.

Import / Traverse 1

Import / Traverse 2


Point label match (default)

This is the default method, in which TPC allows you to record any number of GNSS observations to existing GNSS survey points.

The first GNSS observation to a survey point is allowed to compute the position of that point.  Additional GNSS observations to that point simply hold the observed data without computing their own position for that point.  The additional GNSS observations, are however, included in computing the average position for that survey point.

If your data collector allows redundant observations to existing survey points, TPC will automatically create corresponding redundant GNSS observations when you import that data into TPC.

Example

In Traverse 2 above, G10048, G761, G763, G763B and G763A use this method and refer to their existing survey points in Traverse 1.

In Traverse 2, TPC shows the raw data like RMS X and Count for this particular observation, but shows the current survey coordinates for those points established by Traverse 1. Redundant GNSS observations, like these in Traverse 2, do not compute positions for their existing points, they just store the raw data for the observations.


Point label contains

This method assumes that redundant GNSS observations are identified by some matching character or string in their point labels, as in the following examples.

GNSS point label 100 could have redundant GNSS observations with point labels 100@, 100@1, 100@2 all of which are redundant GNSS observations for point 100.  You would just tell TPC that the @ symbol identifies redundant observation points.

Observed GNSS point G100 would related back to GNSS point 100 if you specified G as the matching string.

This convention allows a GNSS point to be observed any number of times, with each observed position being associated to it.

Example

In Traverse 1 and Traverse 2 above, points G761 could be redundant GNSS observations to a GNSS point 100 that already exists in the survey if the letter G were specified as the matching string.


Point label difference

This method assumes that all your GNSS point labels are numbers, or start with numbers and that point labels for additional GNSS observations are incremented by some number offsets as in the following example.

GNSS point label 100 could have additional GNSS observations with point labels 1100, 2100, 3100 all of which are observed positions for design point 100.  You would just tell TPC that the difference of 1000, 2000 or 3000 identifies the GNSS point.

This method allows you to easily report sequences of repeated stakeouts. For example

On Monday, you use 1000 as the offset for all your GNSS points.

On Wednesday, when you go back out to re-measure those same points, you use 2000 as the offset.

On Friday, you would use 3000 as the offset.


Point description contains

This method assumes that GNSS points are identified by some matching character or string in their point descriptions, as in the following examples.

GNSS point label 100 could have any number of observed points with point, each with #100 in their point descriptions.

Any character, like # can be used to identify the point labels in the description and other information can be included in the description either before or after the #[design point label].

Example

In Traverse 1 and Traverse 2 above, points G761 could be redundant GNSS observations to a GNSS point 100 that already exists in the survey if the = character were specified as the matching point label character used in descriptions.


GNSS Averages

If GNSS averages are computed, the redundant GNSS observations in Traverse 2 will be combined with the GNSS observations in Traverse 1 to compute average positions for each point.  Those averaged positions will then be displayed in their respected Traverse Views.

See Averaging GPS/GNSS.


Related Topics

Averaging GPS/GNSS
How TPC Stores GPS/GNSS Data

Editions

Premium, Professional

 

 

 

Copyright © 2024 Traverse PC, Inc.