Nikon NPL-632, Инструкция по эксплуатации

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Field Station NPL-632 Instruction Manual 117
Menu Key 5
Sea Level correction
Curvature and Refraction correction
Because the surface of the earth is curved, the vertical difference (VD and Z) at the
measurement point, as referenced to the horizontal plane, inevitably includes some
error. This error is called
curvature error . Also, because the density of the air
surrounding the earth decreases with altitude, light is refracted at different rates at
different altitudes. The error caused by this change in refraction is called
refraction
error .
HD Horizontal dist. (before adj.)
HD'
Horizontal dist. (after adj.)
Z
STN
Instrument-Z
R
e
6370 km
HD Horizontal dist. (before adj.)
HD' Horizontal dist. (after adj.)
VD Vertical dist. (before adj.)
VD' Vertical dist. (after adj.)
SD Slope dist.
VA Vertical angle
R
e
6370 km
k C&R constant (0.132 or 0.200)
HD'
HD R
e
×
R
e
Z
STN
+
------------------------
=
Curvature error (A A
'
) Refraction error (A A1
'
)
P
A
'
Horizontal
direction
A
O
P
A1
'
A1
A
'
HD' HD
SD
2
2VA
( )
sin
2R
e
----------------------------------- 1 k
2
---
–
⎝ ⎠
⎛ ⎞
– =
VD' VD
HD
2
2R
e
----------- 1 k
–
( )
+ =