Topcon GTS-710 Series, Manual

Page: 59 / 92

10 SETTING ATMOSPHERIC CORRECTION
10-51
8
檢驗與校正
8.1
儀器常數之檢驗與校正
Normally, the instrument constant does not have discrepancy. It is recommended you
measure and compare with an accurately measured distance at a location where the
precision is specifically monitored on a consistent basis. If such a location is not available,
establish your own base line over 20m (when purchasing the instrument) and compare
with the data measured with newly purchased instrument.
In both cases note that the setup displacement of the instrument position over the point),
the prism, baseline precision, poor collimation, atmospheric correction, and correction for
refraction and earth curvature determine the inspection precision. Please keep in mind
these points.
Also, when providing a base line in a building, please note that the difference in
temperature greatly changes the length measured in the building.
If a difference of 5mm or over is the result from the comparative measurement, the
following procedure as shown below could be used to change the instrument constant.
c
Provide point C on a straight line, connecting straight line AB which is almost
horizontal and about 100m long, and measure straight lines AB, AC and BC.
d
Obtain the instrument constant by repeating - above several times.
Instrument constant=AC+BC-AB
e
When there is error between written instrument constant value and calculated value,
review the Chapter 8.7 "How to Set the Instrument Constant Value" procedure.
f
Once again, measure at a calibrated baseline and compare with the instrument base
line the length.
g
If using above procedure and no difference is found from the instrument constant at
the factory or a difference of over 5mm is found, contact TOPCON or your TOPCON
dealer.
C
A B