ArduRover + PixHawk + GPS RTK WITHOUT telemetry: 4G connection


I’m making a rover and I need to use GPS RTK.
In France we have a free RTK network (Centipède), so to acces them from the rover I need to get mobile connexion, such as 4G connexion.

I’m searching from several days the righ architecture, but doesn’t find a architecutre WITHOUT Mission Planer / Qgroundcontrol for connecting to NTRIP caster.

My goal is only rover + pixhawk + F9P + 4G connexion, no connexion via Telemtry to Mission Planer during Mission.

I would like to make this architecture : F9P > PixHawk > RPI > 4G Connexion
But I dosen’t find how I can send the RCTM3 frame from RPI to PixHawk.

Do you know how I can do ?

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Try mavproxy to send RTCM3 to the autopilot.

Or you could use a Ntrip client something like this GitHub - Coffeetrac/AG_NTRIP_ESP: AG Rooftop controller with NTRIP client and IMU (ESP32 Controller)

I think mavproxy is overkill if used only for RTCM and sometimes, at least in my case, it has been very very unstable and shutting down RTCM for no reason.
Been using str2str for nearly 2 years now with no probs at all, very reliable.


Figured MAVProxy might be a readymade solution that is well documented. I’ve used ser2net on a Raspberry Pi as a much lighter weight solution with a great deal of success, as well.

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ser2net to do what? I guess i don’t understand.

Serial RTCM3 → R Pi → ser2net → network connection → companion or GCS computer → autopilot

Perhaps I’m thinking a bit too complex, though. With an onboard companion and a cell connection, it could connect directly to the NTRIP server and then output over UART to the autopilot.

Ah ok. I was talking about str2str, part of rtklib. Can connect to a cors and stream connection out. So it is ideal for 4g connected raspberry.
Really takes 5 minutes to setup on a raspberry.
(i am about half way trough your lua video tutorial. Really nice, thanks).


Thanks a lot for your answer.

just for clarification : in all case, the computing of the RTCM3 frame is made IN the GPS F9P module ?

(it’s not my use case, but just to clarify : So when we send RTCM via Telemetry, pixhawk just transfer the frame to the F9P and then F9P return corrected position ?)

Yes. The autopilot is just a conduit for RTCM3 to the GPS modules, and it can be transmitted externally as needed.


thank you for this topic, it has been really helpful for me to understand how to use RTKLIB properly ! I just have a question for my understanding: I set str2str has proposed by Corrado_Steri on my computer and I receive the information from the Ntrip server.

To get proper positioning I need one str2str which request RTCM data to the Ntrip server and one str2str which send the position in NMEA from the GNSS device to the Ntrip server ?

Hi Hexor,

I am trying exactly the same thing. Did you get it to work? any advice?