> For the complete documentation index, see [llms.txt](https://horus-make-sense.gitbook.io/documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://horus-make-sense.gitbook.io/documentation/tutorials/working-with-horus-recordings/quality-checks/gnss-accuracy-and-trajectory.md).
# GNSS Accuracy & Trajectory
## Applanix Log
Applanix has two methods for checking the accuracy of the driven trajectory.\
POSPac Assure is their online method, whilst POSPac MMS is their full desktop based application for processing this data.
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{% tab title="POSPac Assure" %}
POSPac requires an internet connection.\
A demo video can be viewed [here](https://youtu.be/s1VqATvU5aQ?si=VzK8GO_fn0pCTLCW).
* Go to the [POSPac Assure website](https://applanixpospacassure.com/projects).
* You may need to log in with a Trimble account.\
* Drag the log onto the input box, and click on 'Submit Project'.\
The upload may take a few minutes.\
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Features can be set to 'Real Time QC'.\
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When finished uploading the trajectory will be shown on the map.
* When finished go to the project page.\
* When the log has finished processing, click on the download button.
* Extract the .zip and open the .pdf file\
Scroll down to the page showing the "RealTime RNAV Performance Metrics".
* This graph shows the estimated accuracy of the raw data on the left in meters.\
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Check for the peaks, if there is one it should quickly go back down to the average.\
If the value goes into the double-digits, then this could affect the final result.\
If the average or a considerable part is in the double digits, then consider the best practices for the Applanix and this may lead to inaccurate data, even after post-processing.\
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The values are not final. during the post-processing these will improve.
{% endtab %}
{% tab title="POSPac MMS" %}
**POSPac MMS**\
In POSPac MMS you can verify the estimated accuracy of the collected data.\
For more information, see the POSPac post-processing workflow page.
* Open POSPac MMS.
* Import the log file.
* (Optional) Process the data.
* Go to Reports -> Display Plots\
* Open the "Real Time Performance Metric, Vehicle Frame" tab and select both the **North** and **East Position Error.**\
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If you did process the data then you can also view the estimated accuracy of the corrected trajectory.\
Open the "Smoothed Performance Metrics, Reference Frame" and then select both the **North** and **East Position Error.**\
* **Pre-Processed**\
Check for peaks, if there is one it should quickly go back down to the average.\
If the value goes into the double-digits, then this could affect the final result.\
If the average or a considerable part is in the double digits, then consider the best practices for the Applanix and this may lead to inaccurate data, even after post-processing.
* **Post-Processed**\
If processed with RTX or Base station data, then expect the average accuracy to be <5cm.\
Some peaks are normal, but they should quickly fall back to the average.
{% endtab %}
{% endtabs %}
