Technical data

6 Post-Process GPS Surveying
location, 7-10 GPS satellites may be visible and available for use, although the
GPS system does not require this many satellites to function. Accurate and
reliable positions can be determined with five satellites properly distributed
throughout the sky. Therefore, an obstructed location can be surveyed if at least
five satellites can be observed. This makes GPS use possible along a tree line or
against the face of a building, but only if that location leaves enough of the sky
open to allow the system to observe at least five satellites.
Ashtech Z-Xtreme Survey System
The Z-Xtreme Survey System is Ashtech’s most advanced post-process survey
system. The system includes all required components to perform post-process
GPS surveys. The Z-Xtreme Survey System is built around the Ashtech Z-
Xtreme dual-frequency GPS receiver. Being a dual-frequency receiver (utilizes
satellite signals on both L1 and L2 frequencies), the Z-Xtreme makes your GPS
system more versatile and productive compared to a post-process GPS system
based on a single-frequency GPS receiver. A dual-frequency system requires
shorter observation times on point for static surveys, requires less time to
initialize, less effort to remain initialized during kinematic surveys, and will
maintain the highest level of accuracy even when surveying points separated by
20 kilometers or more. There is no more advanced post-process survey system
than one based on the Z-Xtreme dual-frequency GPS receiver.
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