18
confirm and calibrate. Caution: If the difference is too large, the
system will suggest resetting the i angle. Press
OK
to continue, or
Back
to return to the calibration again.
Tips: If necessary, please repeat the calibration of i angle according
to the steps above.
9.2
Correction of Additive Constant
Caution: Do not change the constant if unnecessary.
The additive constant is relatively stable. We suggest inspecting it
once or twice a year. You can follow the following steps to do a
quick inspection and correction.
Inspection
Step 1: Set the instrument on a flat ground, mark it as Point A.
Along the vertical crosshair, mark Point B and C with a space of 50m
on the same line. Set reflectors on Point B and C precisely.
Step 2: Set the temperature and air pressure in the system, and
measure the horizontal distances of AB and AC accurately.
Step 3: Set the theodolite on Point B and level it precisely. Measure
the horizontal distance of BC accurately.
Step 4: Now we can get the additive constant by the following
formula.