Hi
Using the Septentrio Mosaic-Go with dual antennas in order to get heading from GPS.
I can’t find information about how to configure EKF2_GPS_POS_X/Y/Z when using a dual heading GPS.
Should it be set according to the master antenna position, the GPS receiver module (the mosaic-go) or should it be the point in between the antennas?
the septentrio gnss dual antenna provides the gps position information in the cop (center of phase of the main antenna)
Thanks for information. Where did you find this information? It makes physical sense but what says e.g the 2 antenna positions aren’t fused and the midpoint is reported.
I’m using a Septentrio Mosaic-H module with a dual-antenna setup, and based on my own testing, I can confirm that the second antenna is used solely for heading calculation. The module determines the orientation using the baseline between the two antennas. However, the GPS position output by the module—such as the one provided through the NMEA, SBF message—corresponds only to the position of the primary antenna.
I verified this by comparing the Mosaic-H’s position output with a second single-antenna RTK receiver. I placed that receiver exactly at the position of the main antenna first, then at the position of the secondary antenna. In both cases, I compared the coordinates with the values reported by the Mosaic-H. What I observed is that the reported GPS position matched the location of the primary antenna precisely, and did not reflect any influence from the secondary antenna. This clearly confirms that the secondary antenna plays no role in the position output—it’s used exclusively for determining heading
Thank you for the in depth answer! 
Then I’ll change my ekf2 gps positions and do some test flights.
Do you think this is how all dual gos work? E.g the holybro UM982 dual gps aswell?