Spectra Precision Survey Pro v4.6 Recon and Nomad User Manual - Manual (Page 303)

GPS Module
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the local coordinate system, it is not possible to compare the geodetic
coordinates from the different sets of data.
Survey Pro solves this problem by assigning a set up group each time
a new autonomous base is set. A set up group is a unique flag
attached to each point record generated by GPS. Setup groups are
assigned as follows:
• When you set a new base point with an autonomous GET, Survey
Pro creates a new set up group for this point.
• When you collect geodetic measurements, each new point is
assigned the set up group of the current base station.
• When you set the base on an existing point with geodetic
coordinates, the point’s existing set up group is used as the new
base station set up group.
• When you set the base on a point with existing plane coordinates
and compute geodetic coordinates using the ‘Move Base’
algorithm, the existing coordinate system’s set up group is used
as the new base station set up group.
One Point Localizations Explained
When you want to open a new job and start a ground level survey
with no existing coordinates or control, you should use the Start GPS
Survey wizard one point setup option. After you set your base and
rover, you will be ready to collect data in a coordinate system with the
following properties:
• The coordinate system is scaled to ground level. Distances
measured with an EDM will be 1:1 with GPS measured
coordinates. Ground level is set automatically at the base
reference position. If your base is set at a height considerably
higher or lower than your survey area, use the Localization Set
Zone screen (Page 249).
• The coordinate system is oriented with grid north equivalent to
geodetic north at the base point. This means if you did a sun shot
at the base reference position; your solar azimuth would be
equivalent to grid azimuth along this meridian. If you did a sun
shot east or west of the base position, the solar azimuth would
differ from grid azimuth by meridian convergence.