Sokkia CX Series Operator's Manual page 251

• If horizontal distance is requested when selecting "T type" or by the GTS
command, uncorrected "ground distance" is output, regardless of the Sea level
correction or Scale factor setting.
Automatic tilt angle compensation mechanism
The vertical and horizontal angles are automatically compensated for small
tilt errors using the 2-axis tilt sensor.
• Read the automatically compensated angles when the display has
stabilized.
• The horizontal angle error (vertical axis error) fluctuates according to the
vertical axis, so when the instrument is not completely leveled, changing
the vertical angle by rotating the telescope will cause the displayed
horizontal angle value to change.
Compensated horizontal angle = Measured horizontal angle + Tilt in angle
/tan (Vertical angle)
• When the telescope is directed close to the zenith or nadir angle, tilt
compensation is not applied to the horizontal angle.
Collimation correction
The CX has a collimation correction function that automatically corrects
horizontal angle errors caused by horizontal axis and leveling axis errors.
Sea level correction
The CX calculates horizontal distance using slope distance values. As this
horizontal distance does not take height above sea level into consideration,
performing spherical correction is recommended when measuring at high
altitudes. Spherical distance is calculated as follows.
( )
------------------ -
HDg =
(
R
Where: R = radius of the spheroid (6370000.000m)
H= averaged elevation of the instrument point and target point
HDg=Spherical distance
HD = horizontal distance
*1 The averaged elevation is automatically calculated from the instrument
point elevation and the collimation point elevation.
R
×
HD
)
+ H
33. CHANGING THE SETTINGS
241