Spectra Precision Focus 30, User Manual

Page: 90 / 126

6 Instrument Technology
74 Spectra Precision FOCUS 30 User Guide
Angle Measuring Technology
The principles of angle measurement are based on reading an integrated signal over
two opposite areas of the graduated circle and producing a mean angular value. This
eliminates inaccuracies caused by eccentricity and graduation.
In addition, the angle measurement system compensates for the following automatic
corrections:
• Instrument mislevelment (deviation of the plumb axis).
• Horizontal and vertical collimation error.
• Trunnion axis tilt, see Correction for Trunnion Axis, page 76 .
Correction for Mislevelment
The Spectra Precision FOCUS 30 Total Station automatically corrects for mislevel-
ments up to ±5,5’. The instrument warns the operator immediately of any mislevel-
ments in excess of ±5,5’(±0.1 grads).
Corrections for the horizontal angle, vertical angle, and slope distance are calculated
in the field application software and applied to all measurements.
Compensator Calibration
The calibration process involves the instrument automatically reading the compensa-
tor value at a series of predetermined positions through the full rotation of the instru-
ment. The process takes approximately one minute to complete. During the process
the instrument should be on a stable platform, free from vibration and untouched by
the user.
Spectra Precision recommends that you regularly carry out a compensator calibration,
especially
Spectra Precision recommends that you regularly carry out a compensator calibra-
tion, especially in the following situations:
• Whenever the instrument may have been roughly handled during transport.
• When the ambient temperature differs by more than 10°C (18°F) from the
previous collimation test.
• Immediately prior to high precision angle measurements in one face.