The following automatic corrections are made:
•
Line of sight error
•
Tilting axis error
•
Earth curvature
•
Circle eccentricity
•
Compensator index error
•
Vertical index error
•
Standing axis tilt
•
Refraction
•
ATR zero point error
7.8
Scale Correction
By entering a scale correction, reductions proportional to distance can be taken
into account.
•
Atmospheric correction.
•
Reduction to mean sea level.
•
Projection distortion.
The slope distance displayed is correct if the scale correction in ppm, mm/km,
which has been entered corresponds to the atmospheric conditions prevailing
at the time of the measurement.
The atmospheric correction includes:
•
Adjustments for air pressure
•
Air temperature
•
Relative humidity
For highest precision distance measurements, the atmospheric correction
should be determined with an accuracy of 1 ppm. The following parameters
must be redetermined:
•
Air temperature to 1 °C
•
Air pressure to 3 mbar
•
Relative humidity to 20 %
The air humidity influences the distance measurement if the climate is
extremely hot and damp.
For high precision measurements, the relative humidity must be measured and
entered along with the air pressure and the temperature.
ppm
+5
+1
+2
+3
+4
+0
-10
-20
0 10 20 30 40 50
°C
100%
80%
60%
40%
20%
TS_104
pp
m
Air humidity correction
[mm/km]
% Relative humidity [%]
C° Air temperature [°C]
Type
Index n
Carrier wave [nm]
Combined EDM
1.0002863
658
Automatic corrections
Use of scale correc-
tion
Atmospheric correc-
tion
D
D1
Air humidity
Air humidity
correction
Index n
64
Technical Data
