GeoMax Zoom90 - Page 54

Zoom90 | 54Technical Data
Formulas The instrument calculates the slope distance, horizontal distance, height difference in accordance with the
following formulas:
Earth curvature (1/R) and mean refraction coefficient (k) are automatically taken into account when calcu-
lating the horizontal distance and height difference. The calculated horizontal distance relates to the
station height and not to the reflector height.
Displayed slope distance [m]
D
0
Uncorrected distance [m]
ppm Atmospheric scale correction [mm/km]
mm Additive constant of the reflector [mm]
Horizontal distance [m]
Height difference [m]
Y * |sin|
X * cos
 Vertical circle reading
A (1 - k/2)/R = 1.47 * 10
-7
[m
-1
]
B (1 - k)/2R = 6.83 * 10
-8
[m
-1
]
k 0.13 (mean refraction coefficient)
R 6.378 * 10
6
m (radius of the earth)
TS_111
= D
0
· ( 1 + ppm · 10
-6
) + mm
TS_112
= Y - A · X ·
Y
TS_113
= X + B · Y
2