Scale Correction - Leica TS12P User Manual

7.9
Use of scale
correction
Atmospheric
correction D1
Air humidity
Air humidity
correction
Index n
TS12P, Technical Data

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 redeter-
mined:
• 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
+4
+3
+2
+1
+0
-20 -10 0 10 20 30 40 50
TS_104
Type
combined EDM
The index n is calculated from the formula of the IAG Resolutions (1999), and is valid
for:
Air pressure p:
Air temperature t:
Relative air humidity h:
100%
80%
60%
40%
20%
ppmAir humidity correction [mm/km]
% Relative humidity [%]
°C
C° Air temperature [°C]
Index n
1.0002863
1013.25 mbar
12 °C
60 %
carrier wave [nm]
658
68