5 Measurement Guidelines
5.1 General Measurement Guidelines
Selecting a levelling staff
The measuring accuracy depends on the levelling staff that is used in combin-
ation with the instrument. Use standard levelling staffs for medium range of
accuracy and (calibrated) Invar levelling staffs (for example GPCL3) for highest
precision.
☞
When using an Invar levelling staff, adjust the Staff Select setting to
maintain highest precision. Refer to 6.1 Work Settings.
Preparing a Measurement
•
Allow the instrument to acclimatise to the ambient temperature. Wait
approximately 2 minutes per °C of temperature difference.
•
When working under strong sunlight with the instrument remaining on
one station for a long time, for example when measuring or setting out a
grid, use an umbrella to shield the instrument and the tripod.
•
Keep the optics clean. Dirt or condensation on the optics can affect
measurements.
•
Check and adjust the instrument regularly; especially after long storage
periods, after transportation or before an upcoming high precision level-
ling task. Refer to 14 Check & Adjust
•
Depending on the planned measurement task, set or change relevant
instrument parameters, such as earth curvature correction or measure-
ment mode.
Taking a measurement
•
Maintain approximately the same target distance for back- and foresight.
At the end of a line, check if the sum of all foresights equals the sum of
all backsights.
•
Measure foresights and backsights. When closing a line at a known end
point, check the misclosure between the measured total delta height and
the delta height calculated from the difference between start and end-
point height.
General Guidelines
Measurement Guidelines 31
To Next Page
