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In summer 2004 the
infrastructure was put in place for a electronic distance measurement (EDM)
system and a differential global positioning system (dGPS). This system will be completed in summer
2007 and will comprise of 4 common pillars with both GPS and EDM prisms, 2
installations with just dGPS receivers and up to 20 locations of prisms on
the face of the mountain. The distance
between the prisms and a fixed robotic total station (survey instrument),
located in the base of the valley, will be repeatedly recorded so that point
source deformations can be observed.
The locations of these prisms will be tied in with the prisms on the
combined GPS/EDM pillars to get absolute locations of the prisms, thus
minimizing the requirement for atmospheric corrections.
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