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Glossary
GNSS: Global Navigation Satellite System. Standard generic term
for satellite navigation systems that provide autonomous geo
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spatial positioning with global coverage. This term includes e.g.
the GPS, GLONASS, Galileo, Beidou and other regional systems
WAAS: Wide Area Augmentation System. Air navigation aid de-
veloped by the Federal Aviation Administration to augment the
Global Positioning System (GPS), with the goal of improving its
accuracy, integrity, and availability.
EGNOS: European Geostationary Navigation Overlay Service. Pan
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European satellite navigation system. It augments the US GPS
satellite navigation system and makes it suitable for safety critical
applications.
VWC: Volumetric Water Content. The percent of the soil volume
that is filled with water. At saturation, the VWC will equal the soil
porosity.
EC: Electrical Conductivity. A measure of how well the soil solu-
tion conducts electricity. The EC is influenced by the amount of
salt and water in the soil.
TDR: Time Domain Reflectometry. A technique for measuring soil
moisture content that uses the fact that water has a much higher
dielectric permittivity than air, soil minerals, and organic matter.
