Characterization of multipath phase rates in different multipath environments

A well-known effect of multipath propagation is multipath fading that typically causes periodic signal variations. Such signal variations may become visible in some basic GNSS observables such as the code minus carrier observable, single or double differences or in C/N ₀ time series. The frequency of these variations—also called fading frequency or multipath phase rate—strongly depends on the multipath environment, i.e. on the actual geometric conditions which can be described by the location of the satellite causing the multipath signal and the reflector location with respect to the receiving antenna. This paper gives a detailed insight on the expected multipath phase rates in different multipath environments. Different geometric conditions are analyzed, from arbitrary reflector positions to the point of dealing with the special case of ground multipath. Fading frequencies are determined by means of an empirical approach using the characteristics of real satellite passes. The approach results in distributions of multipath phase rates which are computed for a multitude of possible reflector locations and from which minimum, mean and maximum multipath phase rates can be derived.