Spectra Precision Survey Pro v4.5 Ranger User Manual - Manual (Page 266)

User’s Manual – GPS Mode
256
subsequent solutions. If the checkpoint measurement is within
the tolerance, this step should not be necessary.
• Redundancy and residuals: After solving localization parameters
with more than the minimum number of control points, you
should examine the solution residuals. The residuals should be
close to the measurement precision of your instrument and the
control points.
Ground - TDS Localization Explained:
When the horizontal projection mode is Ground - TDS Localization, a
default map projection is automatically set up to produce ground
coordinates at the base station height. The Ground - TDS Localization
mode default map projection is an oblique stereographic map
projection with the following parameters:
o
Origin is at the initial base station location
o
False northing and false easting of 100000.0 m
o
Scale at the origin of the stereographic map projection zone is
calculated to produce ground scale distances at the height of
the first GPS setup. This projection scale factor is simply the
inverse of the ellipsoid scale factor for the reference height
(see Page 204).
Origin Scale (k
map
) = (R+h)/ R
2
1
2 2
) sin 1 (
φ
e
a
R
−
=
Localization Setup Groups
When you set up different base stations with autonomous positions
from a GET, each position is only accurate to +- 30m (+- 10 m with
Selective Availability (SA) turned off). Geodetic coordinates measured
from your first autonomous base will not be accurately connected to
geodetic coordinates from a different autonomous base. Although the
localization parameters will accurately transform both sets of data to
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