What are Errors Of GPS System?
GDOP(Geometric Dilution of Precision)
The idea of Geometric DOP is to state how errors in the measurement will affect the final state estimation. Geometric Dilution of Precision Estimate of satellite conditions for a given location & time, Given in distance units (meters or feet), When visible navigation satellites are close together in the sky, the geometry is said to be weak and the DOP value is high; when far apart, the geometry is strong and the DOP value is low. Consider two overlapping ring of different centres . If they overlap at right angles, the greatest extent of the overlap is much smaller than if they overlap in near parallel. Thus a low DOP value represents a better positional precision due to the wider angular separation between the satellites used to calculate a unit’s position.
Ideal GDOP: One Satellite directly overhead w/an abundance of additional satellites spaced evenly around the sky
