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How can I get the heading of the vehicle versus the heading of the motion


I have a fixed base station (SIRIUS XXL) and a rover (TinyRTK) that can go to FIXED within 2 minutes, but I can’t seem to get a reading for the heading of vehicle. I only get the heading of motion while my vehicle heading according to UBX-NAV-PVT is always “n/a”. I know that one way I can calculate the heading of vehicle is if I have 2 antennae, but I think I should be getting a heading of vehicle by just configuring the base and rover somehow. I send rtk corrections over ntrip and I’ve been able to get a FIXED from my current configurations. What other configuration parameters should I be looking at?

Thank you,

Hi Trixie,

In u-center, once your are in fixed mode while connected to the rover, you may be able to get the heading value between base and rover using the RELPOSNED register.
To do so, go to “View” -> “Messages View” -> go down to “UBX” -> click on the ‘+’ and then “NAV” -> “RELPOSNED (Relative Position NED)”
You can then have access to the heading and relative distance from base to rover.
If not, you need to configure your base and rover using a moving base configuration, see here :


Hi Paul,

I don’t seem to get the Heading either on the RELPOSNED option (it’s grayed out
0. I will have to try the moving base guide. The config files would still be exactly the same for my NEO-M8P base and rover?

Much thanks,

Hi Trixie,

Ok so to get the heading value between your moving base and the rover :

  • First go to here :
  • Then download the whole folder (Upper right green tab “Download”)
  • Then you need to configure your “Moving base” (that actually can be either static or moving during the mission) using the file F9P Base moving base config C99.txt located in ublox-C099_F9P-uCS/zed-f9p
  • Finally, configure the rover using the file called F9P Rover config C99.txt located in the same folder

Now you should be able to get some values under the RELPOSNED registry from the Rover.