Hi @dave1,
Sorry, it was so quiet here. I agree with @Gabriel_C. The rover’s height is related to the same datum as your base. Thus, it’s vital to enter the correct ellipsoidal height.
It’s possible to enter the base position with orthometric height. You can create a project with the WGS84 coordinate system and select the proper geoid model. Then, add your known point by entering its coordinates. So, while setting your base, you can select this point from a project. Emlid Flow will convert these coordinates into geographic ones.
We have a support tip about setting the base using local coordinates and orthometric height.