10 SETTING ATMOSPHERIC CORRECTION
10-1
10 SETTING ATMOSPHERIC CORRECTION
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 1013.25hPa / 760mmHg / 29.9 inHg is as a standard value for
0ppm in this instrument. The values are kept in the memory even after power is OFF.
●
Setting the atmospheric correction value is in the STAR key (
★
) mode.
10.1 Calculation of Atmospheric Correction
The followings are the correction formulas.
Unit; meter
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 Temperature +20°C, Air pressure 847hPa, l =1000 m
+
50
×
10
-6
(50 ppm)
L
= 1000 (1+50
×
10
-6
) = 1000.050 m
10.2 Setting of Atmospheric Correction Value
●
How to Set Temperature and Pressure Value Directly
Measure the temperature and air pressure surrounding the instrument beforehand.
●
Example : Temperature: +26°C, Pressure:1020 hPa
Operating procedure Operation Display
1
Press STAR (
★
) key.
[
★
]
2
Press [F6] (
↓
)key to get the function as in
page 2.
[F6]
[F3]
3
Press [F3] key.
Current setting value is displayed.
[F3]
Enter
Temp.
[ENT]
4
Input Temp.value and press [ENT]key.
[Example] Temp. : +26.0
°
C
The cursor moves to Pressure setting
automatically
Ka: Atmospheric correction value
P : Ambient atmospheric pressure (hPa)
t : Ambient Atmospheric temperature (°C)
Ka
279.67
79.535
P
×
273.15
t
+
-------------------------------–
10
6
–
×
=
Ka
279.67
79.535 847
×
273.15 20
+
----------------------------------------–
10
6
–
×
=
2001-07-10 14:30:40
1
↓
3
2001-07-10 14:30:40
2
↓
20.0 °C
5.1ppm
0.0 mm
1012.0hPa
Temperature setting
To Next Page