Multipath

Multipath is a signal propagation effect in which GNSS signals reach the receiver antenna not only via the direct path from the satellite but also after reflection from nearby surfaces such as buildings, water, or the ground. These reflected signals interfere with the direct signal and introduce errors in the measured pseudorange and carrier phase observations.

In geodesy, multipath is a significant error source that can degrade positioning accuracy, especially in high-precision GNSS applications. It can introduce centimeter-level errors in station coordinates and affect time series used for crustal deformation and reference frame realization. Careful site selection, antenna design, signal processing techniques, and multipath modeling are essential to mitigate its impact on geodetic measurements.