User's Guide _______________________________________________________________________
184 __________________________________________________________________ M211107EN-C
Remove calibrator assembly and type
YES: YES
1>
Scatter Signal Test was
skipped.
PWD32 Forward Scatter Calibration
The optics calibration is checked and adjusted with the PWA11
calibration kit. The kit consists of a blocking plate and two opaque glass
plates with known scatter properties. The ZERO, CHEC, and CAL
commands are used in the procedure. The calibration procedure checks
two points; zero scatter signal and a very high scatter signal. The zero
signal is obtained using a blocking plate and the high signal using opaque
glass plates.
When the optical measurement is calibrated, visibility should be better
than 500 meters. Calibration is not recommended to be carried out in
heavy rain or in bright sunshine. Bright sunlight on the calibrator plates
will increase noise in the scatter measurement and make the CHEC
command output less stable. However, light rain does not matter.
PWD32 Calibration Check Procedure
Clean the lenses following the instructions in section Cleaning Lenses
and Hoods on page 171 before the calibration check procedure. Also
check the condition of the opaque glass plates and clean them if
necessary.
1. For blocking the light path, place the blocking plate in the receiver
hood and wait for 30 seconds.
2. Give the ZERO command. PWD32 should answer as follows:
ZERO SIGNAL: OK>
3. Remove the blocking plate.
4. Install the calibrator plates to the lens hoods. Refer to Figure 50 on
page 185.
5. Pay attention to the signal value printed on the plates because it is
needed during the following steps.
6. Move away from the optical path and wait for 30 seconds.
7. Give the CHEC command.
8. After one minute, read the displayed signal.
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