185
33. CHANGING THE SETTINGS
t: Air temperature (
°
C)
p: Pressure (hPa)
e: Water vapor pressure (hPa)
h: Relative humidity (%)
E : Saturated water vapor pressure
• e (water vapor pressure) can be calculated using the following formula
• The instrument measures the distance with a beam of light, but the velocity of this light varies according
to the index of refraction of light in the atmosphere. This index of refraction varies according to the
temperature and pressure. Near normal temperature and pressure conditions:
With constant pressure, a temperature change of 1°C: an index change of 1 ppm.
With constant temperature, a pressure change of 3.6 hPa: an index change of 1 ppm.
To perform high accuracy measurements, it is necessary to find the atmospheric correction factor from
even more accurate temperature and pressure measurements and perform an atmospheric correction.
It is recommended that extremely precise instruments be used to monitor the air temperature and
pressure.
• Enter the average temperature, air pressure and humidity along the measurement beam route in
"Temperature", "Pressure" and "Humidity".
Flat terrain:Use the temperature, pressure and humidity at the midpoint of the line.
Mountainous terrain:Use the temperature, pressure and humidity at the intermediate point (C).
If it is not possible to measure the temperature, pressure and humidity at the midpoint, take such
measurements at the instrument station (A) and the target station (B), then calculate the average value.
Average air temperature
: (t1 + t2)/2
Average air pressure
: (p1 + p2)/2
Average humidity
: (h1 + h2)/2
• If the weather correction is not required, set the ppm value to 0.
Select "Obs.condition" in Config mode and select "Other".
33.5 Observation Conditions - Other
E
6.11 10
7.5 t
×
(
)
t 237.3
+
(
)
----------------------------
×
=
e
h
E
100
----------
×
=
Humidity h
1
Humidity h
2
Obs.condition
Angle/Tilt
Dist
Reflector
Atoms
Other
Input order
:
Stn.ID Incr.
: 100
Intersection
:Type B
PT
CODE