# GPRMC message

If the GPRMC output boxed is checked, CeruleanTracker emulates a “GPS” mounted on the ROV by outputting $GPRMC messages with the ROV location and other data.

If a DVL-75 connected to the Ethernet is also broadcasting $GPRMC messages, there will be a conflict between the DVL position and the CeruleanTracker position. CeruleanTracker will warn if a connected DVL-75 is also broadcasting $GPRMC messages and will offer to turn them off if it is.

If you have a Topside GPS attached to CeruleanTracker and you have it set to rebroadcast, it may conflict with other $GPRMC messages depending on what port you have selected.

To summarize, a maximum of one of the following should be set to broadcast $GPRMC messages and/or unicast $GPRMC messages to port 27000 (the used by the BlueROV systems to receive GPS position of the ROV messages)

* CeruleanTracker's output message as selected on the "Output" tab of CeruleanTracker's main window
* A DVL-75's $GPRMC message
* Topside GPS attached to CeruleanTracker as selected on the "Topside GPS" tab of CeruleanTracker's main window (normally the Topside GPS should be assigned to broadcast to port 14401 where QGroundControl expects to receive the position of the ground control station)
* A third-party GPS you have configured to output $GPRMC messages


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