11-1
11 SETTING ATMOSPHERIC CORRECTION
11 SETTING ATMOSPHERIC CORRECTIONThe velocity of light t h rough air is not constant and depends on the atmospheric temperature and
pressure. The atmospheric correction system of this instrument correc t s 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.
lSetting the atmospheric correction value is in the STAR key ( H) mode.
11.1 Calculation of Atmospheric Correction
The followings are the correction form ul as.
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
11.2 Setting of Atmospheric Correction Value
lHow 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
1Press STAR (H) key.
Press the [F6] key twice to get the page three. [H]
[F6] twice
2Press the [F2] key.
Current setting value is displayed. [F2]
3Input Temp.value and press [ENT] key.
[Example] Temp. : +26°C
The cursor moves to Pressure setting
automatically
Enter
value
[ENT]
4Input Pressure value, and press [ENT].
[Example] Pres. :1020.0hPa.
The display returns previous mode.
*1) *2)
Enter
value
[ENT]
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–
×=
2003-10-10 14:30:40
3
↓
20.0 °C 5.1ppm
-2.0 mm
1012.0hPa
Temperature setting
26.0 °C 5.1ppm
-2.0 mm
1012.0hPa
Pressure setting
26.0 °C 5.1ppm
-2.0 mm
1020.0hPa