User's Guide _______________________________________________________________________
30
______________________________________________________ M210296en-A
6.
Installing the base plate and the pole mast:
- Install the base plate with the bolts on the concrete block.
- Level the plate.
- Mount the pole mast on the base plate.
- Mount the junction box to the pole mast (optional). Junction
boxes are available from Vaisala.
7.
Connecting cables:
- Connect the mains and signal cables of the site to the junction
box or have them ready for direct connection to the sensor.
8.
Final installation:
- Install the electronics enclosure and the crossarm of the
FD12P to the pole mast.
- Connect the power and signal cables of the FD12P.
- Connect the modem/signal line to the host computer, display,
etc.
9.
Start-up tests for the system.
Location and Orientation
The main requirements for the location of the FD12P are as follows:
1.
Place the FD12P at a site where the measurements will be
representative of the surrounding weather conditions.
The ideal site has a minimum clearance of 100 meters from all
large buildings and other constructions that generate heat and/or
obstruct precipitation droplets. Also avoid shading of trees as
this may cause changes in the microclimate.
2.
Make sure the site is free of obstacles and reflective surfaces,
which disturb the optical measurements and act as obvious
sources of contamination.
There must not be any obstacles in the line-of-sight of the
transmitter and receiver units (see Figure 4 on page 31). If the
transmitter beam is reflected from obstacles back to the receiver
unit, the sensor will indicate too low MOR values as the
reflected signal cannot be distinguished from the real scatter
signal. Reflections are detected by rotating the sensor crossarm.
They will change depending on the crossarm orientation. Also
the visibility reading will change accordingly.
