# Reference Stations

The primary purpose of a GNSS reference station is to collect GNSS data in the form of raw observations. Raw observations are all measurements recorded by the reference station. If you want to post-process the rover's trajectory, raw observations from the reference station are needed. 

[Set up the GNSS reference station to log differential corrections at intervals of 1 Hz](https://www.phoenixlidar.com/wp-content/uploads/2019/10/PLS_Stonex_S900_Static_Base_Configuration_Via_Web_User_Interface.pdf). A direct connection to the rover is NOT required if you wish to post process your trajectory through PPK NavLab or Intertial Explorer  processing. 

We recommend mounting the reference station antenna onto a survey-grade tripod with a clear view of the sky away from buildings and powerlines. To prevent any discrepancies when measuring the Antenna Reference Point (ARP) height, we recommend a fixed height survey grade tripod. This will ensure a uniform measurement throughout all scanning missions.

1\. Set up the tripod and mount the reference station antenna onto the tripod.

2\. Document the Antenna Reference Point (ARP) height above the ground.

3\. Power the reference station and begin logging GNSS raw observations at 1 Hz. This will allow you to post-process the trajectory in software such as Inertial Explorer or LiDARMill. Stonex S900 users can reference [**Stonex S900 Static Base Configuration Via Web User Interface**](https://www.phoenixlidar.com/wp-content/uploads/2019/10/PLS_Stonex_S900_Static_Base_Configuration_Via_Web_User_Interface.pdf) for more details.

### Further Reading 

* [Ground Control Tips](https://www.phoenixlidar.com/wp-content/uploads/2020/11/Survey-Ground-Control-Recommendations.pdf)
* [Stonex Static Reference Station Configuration Via Web Interface](https://www.phoenixlidar.com/wp-content/uploads/2019/10/PLS_Stonex_S900_Static_Base_Configuration_Via_Web_User_Interface.pdf)


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