# Minimum number of satellites per constellation in Multi-constellation Navigation

Relating to my previous question, I'm trying to understand how the LS method work for multi-constellation GNSS trilateration/multilateration. I understand for 2 constellations, trilateration require at least 5 pseudorange equations to account for the different receiver clock offsets for different constellations.

What is the minimum number of pseudorange equations per constellation? I.e, will one equation for one constellation be enough as long as the total number of equations meet the minimum number required for LS to work?

• Thanks for your comment! I was also thinking the same thing. But I don't really understand why at least 2 satellites from another constellation (and not 1) is needed to account for the inter-system offset. Shouldn't the existence of an additional parameter (say `r_glo` that I used in my previous question) in one satellite already be enough? How will an extra equation with `r_glo` help? Jan 4, 2022 at 13:53