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General
RTK GPS uses a stationary base station unit on the ground (Base) to send correction data to a mobile GPS unit on the aircraft (Rover). The RTK corrections allow the rover unit to achieve a higher level of precision and accuracy than would be possible otherwise.
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Mission Planner has a built-in utility for acquiring and sending RTK corrections. However, this method does not work reliably with newer GPS units. As a result this manual will cover a method of using QGroundControl to generate corrections and then pass them through Mission Planner.
Connection Diagram
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preform a survey-in
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Mission Planner is used to establish a telemetry connection with the aircraft
This is over a network radio or RFD depending on the aircraft configuration
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A Mavlink mirror is opened from Mission Planner
This will allow QGroundControl and Mission Planner to interact with the Mavlink stream from the vehicle simultaneously
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QGroundControl connects to the Mavlink mirror
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of a location or set a pre-surveyed location. Then QGC will be closed and mission planner will be used to pass the corrections through to the vehicle.
Survey-In Position of Ground Station Using QGC
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Position the ground station GPS antenna where it will not be disturbed and with a clear view of the sky.
Connect the base GPS to a Ground Station Computer that will have a wireless link to the aircraft
Open QGroundControl
The program will automatically detect the GPS unit and start a survey-in
The survey-in status can be viewed by clicking the RTK icon in the top menu bar
When the RTK icon turns from red to white, as shown in the image below, the survey is complete and the corrections are ready
Once the survey is complete close QGroundControl
They surveyed location will stay in the F9 unit’s ram memory
Proceed to the “Connecting with Mission Planner” section below
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Do not move the base station after survey-in has begun or during the use of RTK correction data. |
If using a TXMod unit, QGC may automatically detect the connection and block Mission Planner from connecting. In this case click disconnect on QGC then connect with Mission Planner or connect using Mission Planner before opening QGC for the survey.
Change the Survey-In Settings on QGC or Input Pre-Surveyed Coordinates
Click the icon in the top left of QGC window
Click Application Settings
Go to the General menu on the left
Scroll down to the RTK GPS settings
Here you can change the accuracy, time, or input a pre-surveyed location
Restart QGC to make the settings take effect
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Connecting with Mission Planner
Enable the Mavlink Mirror
Connect QGC to the Mavlink Mirror
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QGroundControl will automatically send corrections to any vehicle with an active connection |
Click the icon in the top left of QGC window
Click Application Settings
Go to the Comm Link menu on the left
Click “Add” at the bottom of the screen
Enter the connection information
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Click save
Highlight the desired entry in the Comm Link menu
Click “Connect” to open a connectionLaunch Mission Planner
Select “Setup” from the top menu bar
Go to the “Optional Hardware” section on the left column
Select “RTK/GPS Inject”
Select the COM port for the Base RTk GPS unit from the drop down menu
Select a baud rate of 115200
Check the “Inject MSG Type” and the
Send GGA?” checkboxsLeave the “M8P/F9P autoconfig” checkbox un-checked
Click “Connect”
The red boxes for Base, GPS, Glonass, Beidou, and Galileo should start to turn green
If the “Base” box and one other bx are green then corrections are valid and ready for transmission to the aircraft
Return to the “Data” screen
Connect to the vehicle using a telemetry or data radio modem
Verify the vehicle has an RTK Float or RTK Fix for the status of a GPS unit (as shown in the image below)
