5 research outputs found
Analyse canonique des correspondances et typologie des stations forestières. Une étude de cas
International audienc
Alimentation du cerf (Cervus elaphus) en hiver dans une foret feuillue de plaine
14 ref.National audienc
Changes in forest plant communities with recent climate warming in Jura Moutains (France and Switzerland).
Atmospheric signal propagation
GNSS satellites emit signals which propagate as
electromagnetic waves through space to the receivers
which are located on or near the Earth’s surface
or on other satellites. Thereby, electromagnetic
waves travel through the ionosphere and the neutral
atmosphere (troposphere) which causes signals
to be delayed, damped and refracted as the refractivity
index of the propagation media is not equal
to one. In this chapter, the nature and effects of
GNSS signal propagation in both the troposphere
and the ionosphere, is examined. After a brief review
of the fundamentals of electromagnetic waves
their propagation in refractive media, the effects of
the neutral atmosphere are discussed. In addition
empirical correction models as well as state-of-
the-art atmosphere delay estimation approaches
are presented. Effects related to signal propagtion
through the ionosphere are dealt in a dedicated section
by describing the error contribution of first up to
third order terms in the refractive index and ray path
bending. After discussing diffraction and scattering
phenomena due to ionospheric irregularities, mitigation
techniques for different types of applications
are presented