> For the complete documentation index, see [llms.txt](https://docs-7.phoenixlidar.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-7.phoenixlidar.com/rover/theory-and-workflow/reference-station-setup/spatiallighthouse/initiate-session.md).

# Initiate Session

Press "Start" to initiate data processing. Depending on the configuration, SpatialLightHouse will connect to the reference station, configure it, connect to rover, and forward differential corrections.

If the Start button is grayed out, this indicates that the current configuration is not supported. Here’s how to fix it:

* Check that all required fields are filled.
* When using a serial port to connect to the reference station, if the port does not appear in the list, restart SpatialLightHouse. Available ports are only scanned once on startup, therefore make sure the selected port is listed as free, not busy. A busy port is currently in use by other programs.
* When using the option "Provide differential corrections on a serial port", make sure the selected serial port is not the same port as the port used to connect to the reference station.
* When using NTRIP make sure a stream with supported differential correction format is selected. If the stream requires authentication, make sure the username and password values are populated.
* When using the Phoenix LiDAR Systems connection service, make sure the license key is valid (indicated by a green checkmark).