Topcon GTS-710 Series, Manual

Page: 78 / 92

11 CORRECTION FOR REFRACTION AND EARTH CURVATURE
11-70
11 折射與地球曲率之改正
The instrument measures distance, taking into account correction for refraction and earth
curvature.
Note : If the telescope is positioned within
±
9
°
from the nadir or zenith, no measurement
will result even if the correction function for refraction and earth curvature
works.The display shows "W/C OVER".
11.1
距離化算公式
Distance Calculation Formula; with correction for refraction and earth curvature taken into
account. Follow the Formula below for converting horizontal and vertical distances.
Horizontal distance D=AC(
α
) or BE(
β
)
Vertical distance Z =BC(
α
) or EA(
β
)
D=L{cos
α
-(2
θ
-
γ
)sin
α
}
Z=L{sin
α
-(
θ
-
γ
)cos
α
}
θ
=L
x
cos
α
/2R.............. Earth curvature
correcting item
γ
=K
x
Lcos
α
/2R............ Atmospheric refraction
correcting item
K=0.14 or 0.2............. Coefficient of refraction
R=6372km................. Radius of earth
α
( or
β
) .................... Altitude angle
L ................................ Slope distance
z
The conversion formula for horizontal and vertical distances is as follows when
correction for refraction and earth curvature is not applied.
D=L
x
cos
α
Z=L
x
sin
α
Note : The coefficient of the instrument has been set at 0.14 before shipment (K=0.14).
if the "K" value is to be changed, refer to Chapter 7 "PARAMETERS SETTING
MODE".
Radius of esrth
R = 6372 Km
E
D
C
B
A
-Z
20
20
0
β
α
θ
2
θ