Topcon GTS-710 Series, Manual

Page: 72 / 92

10 SETTING ATMOSPHERIC CORRECTION
10-64
10
大氣改正值之設定
The velocity of light through air is not constant and depends on the atmospheric
temperature and pressure. The atmospheric correction system of this instrument corrects
automatically when the correction value is set. 15
°
C/59
°
F, and 1013hPa /760mmHg
/29.9inHg is as a standard value for 0ppm in this instrument. The values are kept in the
memory even after power is OFF.
z
Setting the atmospheric correction value is in the STAR key ( ) mode.
10.1
大氣改正值之計算
The followings are the correction formulas.
{
Unit; meter
K a
P
t
= −
×
+
×
−
279.66
106.033
273.15
10
6
Ka
: Atmospheric correction value
P
: Ambient atmospheric pressure(mmHg)
t : Ambient Atmospheric temperature(
°
C)
The distance L(m) after atmospheric correction is obtained as follow.
L = l ( 1 +Ka)
l
: Measured distance when atmospheric
correction is not set.
Example : In case Tempe20
°
C , Air pressure 635mmHg, l =1000 m
K a
= −
×
+
×
−
279.66
106.033 635
273.15 20
10
6
≠
50
×
10
-6
(50ppm)
L =1000(1+50
×
10
-6
)=1000.050m