ashtech GG Surveyor, Reference Manual

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42 GG Surveyor GPS+GLONASS Reference Manual
Internally, the receiver implements the transformation from WGS-84 to
WGS-72. Figure 4.10 demonstrates the change in the coordinate systems.
Point Poistioning
The Point Positioning feature improves the accuracy of a stand-alone absolute
position of a stationary receiver to about 4 meters horizontal over a period of about 4
hours, and under 3 meters (horizontal) over a period of about 12 hours. (Figure 4.11).
Point positioning uses an averaging technique to reduce the effects of Selective
Availabiltiy (SA) and other fluctuating errors. Point positioning mode can be set
using the $PASHS,PPO command. We recommend that when using the point
positioning mode that the system be set to use GPS only ($PASHS,SYS command)
Figure 4.10: Rotation and Translation Between Coordinate Systems