Trimble Spectra Precision LL300 - Page 8

9
Inordertoavoidoffseterrors,thereceivershouldbeusedclosetotheelevationwherethelaserhasbeensetup.
Ifaremotecontrolisavailable,theupanddownarrowbuttonscanbeusedforneadjustments.
LEVELING ACCURACY
Inuences on the leveling accuracy
Theoverallaccuracyoftheunitcanbeinuencedbymanyfactors:
• factoryaccuracy;
• temperatureoftheunit;
• ambientinuenceslikerain,windandtemperature.
The factor that inuences on the unit’s accuracy most is the ambient temperature. Vertical differencesin
temperature near the ground can divert the laser beam, similar to the heat waves seen on hot asphalt
streets.
This factor also applies to all optical measuring devices such as automatic levels and
theodolites.
Accuracy Check
Toensurejob-siteaccuracy,youneedadistanceof20m(65feet)betweentwowallsAandB,whereyouwill
execute4measuringoperationsonatripodasfollows(transitmeasurement).
SettheunithorizontallyonatripodnearwallAandswitchitonwiththeplusX-axispointingtowardswallA.
Aftertheunitislevel,marktheheightofthelaserbeamusingareceiveratwallA.Turntheentireunit180°,
letitself-levelandmarkthecenterofthelaserbeamatwallB.
Now,placetheunitnearwallBwiththeplusX-axispointingtowardswallB.Aftertheunitislevel,markthe
heightofthelaserbeamatwallB.Turntheentireunit180°,letitself-levelandmarkthecenterofthelaser
beamatwallA.Thedifference(h)ofthemarkedpointsatwallAshowsthedeviation.
131050_01_LL300_GB.indd 9 30.10.13 08:12