FOCUS 35 TOTAL STATION USER GUIDE
6 –
Instrument Technology
84
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 86
Correction for Mislevelment
The Spectra Precision FOCUS 35 Total Station automatically corrects for mislevelments up to ±5.5’.
The instrument warns the operator immediately of any mislevelments 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 compensator value at a
series of predetermined positions through the full rotation of the instrument. 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 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 calibration
test temperature.
•
Immediately prior to high precision angle measurements in one face.
