During the manufacturing process, the instrument errors are carefully determ-
ined and set to zero. As mentioned above, these errors can change and it is
highly recommended to redetermine them in the following situations:
•
Before 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
error
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
5.2
Preparation
Before determining the instrument errors, the instrument has
to be 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. Take at least 15 minutes into account or approximately
2 minutes per °C of temperature difference from storage to working environ-
ment.
☞
Summary of errors to
be adjusted
electronically
☞
☞
☞
Check & Adjust
37
