•
Be
fore the first use
•
Before every high precision survey
•
After rough or long transportation
•
After long working periods
•
After long storage periods
•
If the temperature difference between current environment and the tem-
perature at the last calibration is more than 20°C
Instrument
err
or
Effects
Hz
Effects
V
Elimination
with two face
measurement
Automatically
corrected
with proper
adjustment
c - Line of sight
error
ü
-
ü ü
a - Tilting axis
error
ü
-
ü ü
l - Compensator
index error
-
ü ü ü
t - Compensator
index error
ü
-
ü ü
i - Vertical index
error
-
ü ü ü
ATR Collimation
error
ü ü
-
ü
5.2 Preparation
Before determining the instrument errors, the instrument has to
b
e levelled using the electronic level.
The tribrach, the tripod and the underground should be stable
and secure from vibrations or other disturbances.
The instrument should be protected from direct sunlight to
avoid thermal warming.
It is also recommended to avoid strong heat shimmer and air
turbulence. The best conditions are early in the morning or with
overcast sky.
Before starting to work, the instrument has to become acclimatised to the
ambient temperature. Approximately two minutes per °C of temperature differ-
ence from storage to working environment, but at least 15 min, should be
taken into account.
Even after adjustment of the ATR, the crosshairs may not be positioned exactly
o
n the centre of the prism after an ATR measurement has been completed.
This outcome is a normal effect. To speed up the ATR measurement, the tele-
scope is normally not positioned exactly on the centre of the prism. These
small deviations/ATR offsets, are calculated individually for each measurement
and corrected electronically. This means that the horizontal and vertical angles
Summary of errors to
be a
djusted
electronically
☞
☞
☞
☞
50 Check & Adjust
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