We are using a Novatel GPS with RTK (and custom GCS or mission planner)
When working this way, with RTK type 6 (FIXED), we cannot set the home position, and we receive the error above.
When working with mission planner, the same thing happens, until the RTK corrections are stopped. At this point the home position can be set, and the error goes away.
The baud rate of the Novatel is set to 460800
@danielm1199 FYI
It seems that part of the problem is that the HDOP value is seen by the Ardupilot to be 168, constant, with no reference to actual fact.
I think that the setup of the Novatel messages is wrong. The PRSDOPB message is actually turned off by the setup, instead of turning it on (the final LOG PRSDOPB command). That’s if these setup commands are run at all.
Eventually we worked around the problem by setting GPS_AUTO_CONFIG to zero, and conmfiguring the Novatel by hand, including
LOG COM1 PRSDOPB ONTIME 2
(Com1 of the Novatel is connected to the autopilot).
With this, the correct HDOP value is shown, there are no errors, correctly and the EKF’s agree to work with GPS.