Sources of Error
Selective Availability is the degradation of the GPS signal by the DoD. The full system accuracy was only available to authorized users (Selective Availability was deactivated on 1st of May 2000).
Both satellite and receiver clocks are not running synchron. The measured ranges are therefore called pseudoranges.
Multipath occurs when part of the signal from the satellites reaches the antenna after reflecting from the ground, a building or another object.
Figure 5.1: Multipath
Abbildung 5.2: Good PDOP
Abbildung 5.3: Bad PDOP
Abbildung 5.4: Atmospheric Refraction
Author: Michael Schulz, GEOSOFT