> For the complete documentation index, see [llms.txt](https://docs.ceruleansonar.com/c/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ceruleansonar.com/c/sonarview/session-configurations/rovl-+-nmea-gps.md).
# ROVL + NMEA GPS
These instructions explain how to use an NMEA GPS for the topside position (ROVL RX) in SonarView
First, go to Session configurations and add a new device with the serial port and baud rate of your GPS\
Then add a new device for your ROVL
The *ROVL Topside Depth* field is the depth of the topside unit below the surface of the water. The *GPS offset from ROVL Topside* is the physical offset from the ROVL topside unit to where the GPS is mounted. The Y axis is in the direction of the indexing notch on the ROVL and the Z direction is in the direction of the cable. Refer [here](/c/rov-locator/rovl-coordinate-systems-and-angles/receiver-transceiver-orientation-frames.md) for the ROVL orientations.\
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Once those are added, add both to a session. You can also add a mavlink vehicle to send position updates to mavlink and get the vehicle orientation in the view. You should be to this point:
And you should be able to discover the session
If everything is working correctly, you should be able to connect and see a white sphere representing your GPS location relative to the topside unit. The topside’s position should update based on the GPS data, provided that the Topside Position Source is set to Automatic. If you did not set an offset between the GPS and ROVL, the white sphere will not show up.