摘要：What does “geometry-based” and “geometry-free” mean in the context of GNSS?
A: The geometry-based model is the usual mathematical model for solving high-precision positions from phase (and code) data using a relative GNSS receiver setup.
The relative receiver-satellite geometry plays a crucial role and has a significant effect on the precision of the parameters to be determined, which are, among others, the carrier phase ambiguities and the relative receiver position.
The geometry-free model dispenses this receiver-satellite geometry: it solves for the receiver-satellite ranges instead of positions. However, ambiguity resolution is still possible using this model.
