Product Manual

13 Calibration
13.1 Overview
GeoMax instruments are manufactured, assembled and adjusted to a high quality. Quick temper-
ature changes, shock or stress can cause deviations and decrease the instrument accuracy. It is
therefore recommended to calibrate the instrument from time to time. This can be done in the
field by running through specific measurement procedures. The procedures are guided and have
to be followed carefully and precisely as described in the following chapters. Some other instru-
ment errors and mechanical parts can be adjusted mechanically.
The following instrument errors can be checked and calibrated electronically:
•
Horizontal collimation error, also called line-of-sight error.
•
Vertical index error, and simultaneously the electronic level.
•
Compensator longitudinal and transversal index errors.
For determining these errors, it is necessary to measure in both faces, but the procedure can be
started in any face.
The following instrument parts can be calibrated mechanically:
•
Circular level on the instrument and tribrach.
•
Laser plummet.
•
Screws on the tripod.
During the manufacturing process, the instrument errors are carefully determined and set to
zero. As mentioned, these errors can change and it is highly recommended to redetermine them
in the following situations:
•
Before the instrument is used for the first time.
•
Before every high precision survey.
•
After rough or long periods of transport.
•
After long periods of work or storage.
•
If the temperature difference between current environment and the temperature at the last
calibration is more than 10°C (18°F).
13.2 Preparation
Before determining the instrument errors, level-up the instru-
ment using the electronic level. The Level & Plummet is the
first screen to appear after turning on the instrument.
The tribrach, the tripod and the ground should be very stable
and secure from vibrations or other disturbances.
The instrument should be protected from direct sunlight in
order to avoid thermal expansion on one side only.
Before starting to work, the instrument has to become acclimatised to the ambient temperature.
Approximately two minutes per °C of temperature difference from storage to working environ-
ment, but at least 15 min, should be taken into account.
Description
Electronic calibration
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Mechanical calibration
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118 Calibration