Spectra Geospatial Focus 35, Руководство пользователя

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6 Instrument Technology
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:
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Instrument mislevelment (deviation of the plumb axis).
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Horizontal and vertical collimation error.
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Trunnion axis tilt, see Correction for Trunnion Axis, page 89 .
Correction for Mislevelment
The 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 Geospatial recommends that you regularly carry out a compensator calibration, especially in the
following situations:
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Whenever the instrument may have been roughly handled during transport.
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When the ambient temperature differs by more than 10 °C (18 °F) from the previous calibration test
temperature.
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Immediately prior to high precision angle measurements in one face.
Correction for Collimation Errors
HA/VA Collimation
The horizontal collimation error is the deviation of the sighting axis from its required position at right
angles to trunnion axis.
The vertical collimation error is the difference between the vertical circle zero and the plumb axis of the
instrument.
Traditionally, collimation errors were eliminated by observing angles in both instrument faces. In the
FOCUS 35 Total Station, a pre-measurement collimation test is performed to determine the collimation
errors. Angular measurements are observed in both instrument faces, the collimation errors are
calculated, and the respective correction values are stored in the instrument. The collimation correction
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