TABLE OF CONTENTS GPS errors are unwanted variations in position measurements that come from a variety of error sources. Without corrections to the errors, the accuracy of the GPS system is approximately 50 to 100 meters. GPS errors include propagation errors that can result from changes in atmospheric conditions, inaccurate satellite position data (ephemeris), reference timing errors (clock drift), multipath transmission and selective availability.
The atmosphere is composed of materials or elements that are surrounding the Earth. The Earth s atmosphere can be divided into layers that have different effects on the propagation of radio signals.
Atmospheric conditions define the characteristics of the atmospheric regions. Atmospheric layers are regions separated by height above the surface of the Earth that contain gasses and materials that share common characteristics. Atmospheric layers include the Troposphere (directly above the Earth to 12 km), the Mesosphere (12 km to 50 km), the Stratosphere (50 km to 90 km), and the Ionosphere (90 km to 400 km).
Atmospheric data is information that identifies the characteristics of the atmosphere. Atmospheric data may be used to define how objects (such as satellites and radio signals) will interact and be changed by the Earth s atmosphere.
Radio propagation is the process of a radio signal (electromagnetic signal) traveling from one point to one or more points. Radio propagation may involve a direct wave (space wave) or a wave that travels along the surface (a surface wave). Radio propagation characteristics typically vary based on the medium of transmission (e.g. Air) and the frequency...
