# Change GNSS constellations

**This step-by-step tutorial will let you to manually change the GNSS constellations for the Base and the Rover.**

First, connect your GNSS device to a computer using a USB micro cable.

![](/files/-LdEnYZLwhXVFEwUuCNY)

Now start the U**-**blox “u-center” software. Then on the top left corner of the screen, left-click on the reversed tiny black triangle to select the COM Port related to your GNSS device. (it may differs from COM7 as shown in pictures)

![](/files/-LYbIddBqnC-aXKJ1bxh)

Make sure the connection icon is blinking in the bottom state bar. It indicates that the serial communication between the computer and the GNSS device is working.

![](/files/-LYbHSKTiJZ0j0qAf-5e)

Next go to ‘View’ then click on “**Generation 9 Configuration View**”

![](/files/-LYbUsIAWEUg8JmCOVN6)

 A new window showing by default “**GNSS Configuration**” opens.

1. So first, if GNSS configuration is not displayed, then click on “**GNSS Configuration**”.
2. You can now have access to all the GNSS constellations and frequency bands.
3. Tick or Untick the GNSS systems as you wish keeping in mind that Nav Update Rate may be affected by the number of GNSS systems activated.
4. Click consecutively on **RAM**, **BBR** and **Flash** to write changes into RAM and both non-volatile memories (BBR and Flash)
5. Click on ‘**Send Configuration**’

![](/files/-LZ5--juD8GAE3118zYL)

{% hint style="success" %}
You have successfully set the GNSS constellations !
{% endhint %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://drotek.gitbook.io/rtk-f9p-positioning-solutions/tutorials/change-gnss-constellations.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.