Topcon GTS-823A User Manual
Page 35
2-11
2 PREPARATION FOR MEASUREMENT
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Prism type-2 (Normal prism)
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Prism type - 3 or 5 (Prism unit A2/A3)
(Example)
In case Prism constant value (C) = 0mm, Prism inclination = 20°, Measuring distance = 100m by Prism
type-2 :
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Distance error is :
From the graph prism type-2, the distance error shows in increasing range quantity 2.5mm along
curved line of C=0 when prism inclination is 20°.
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Angle error is :
From the graph prism type-2, along curved line of C=0 with prism inclination of 20°, find angle error
quantity (14.2mm) and calculate angle error by the following formula.
C=40
C=30
0
30
20
10
22
14
6
-2
0
C=0
( mm )
5
4
2
0
( mm )
C=0
C=30
C=40
6
3
1
-1
30
20
10
0
Distance Measuring error
Angle measuring error
Inclined angle (degree)
Inclined angle (degree)
Increasing
distance
range
Angle error
range
2
18
4
C=30
C=20
C=0
C=20
C=30
10
20
30
-1
0
1
2
3
4
0
C=0
-4
0
8
12
0
10
20
30
( mm
Increasing
distance
range
Angle error
range
Distance Measuring error
Angle measuring error
Inclined angle (degree)
Inclined angle (degree)
( mm)
Angle error
=
Angleerror range
Measuring dis
ce
tan
------------------------------------------------------
-1
tan
=
14.2
100x10
3
--------------------
-1
tan
=29
″