12 CORRECTION FOR REFRACTION AND EARTH CURVATURE
12-1
12 CORRECTION FOR REFRACTION AND EARTH
CURVATURE
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”.
12.1 Distance Calculation Formula
Distance Calculation Formula; with correction for refraction and earth curvature taken into account.
Follow the Formula below for converting horizontal and vertical distances.
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 8 “ PARAMETERS SETTING MODE”.
Horizontal distance D = AC(α) or BE(β)
Vertical distance Z =BC(α) or EA(β)
D = L{cosα—(2θ — γ ) sinα}
Z = L{sinα+(θ — γ ) cosα}
θ = L.cosα/2R........... Earth curvature
correcting item
γ =K
¥Lcosα/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
● The conversion formula for horizontal and vertical distances is as follows when correction for
refraction and earth curvature is not applied.
D=L
¥cosα
Z=L
¥sinα
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