Zero; Chec - Vaisala PWD22 User Manual

Chapter 5__________________________________________________________________ Operation
VAISALA ________________________________________________________________________ 85

ZERO

The ZERO command has no parameters and it is used in calibrating
visibility to display the zero signal status.
When the signal blocker of the PWA11 calibrator kit is installed to the
lens hood of the receiver (box), the PWD22 software checks for the
very low signal and low noise. If the signal or noise is out of the
internal check limits, an error message is shown.
Give the following command:
>ZERO
The output is the following:
ZERO SIGNAL: OK
>
Or in the case of failure in the receiver (PWC22) on e of the
following:
ZERO SIGNAL: FAIL
ZERO SIGNAL: NOISE HIGH

CHEC

The CHEC command has no parameters and it is used in calibrating
visibility to display the one-minute average signal frequency in hertz
(Hz).
The displaying is terminated by pressing ESC. If you press any other
key, the displaying will only be paused. In the beginning, the four-
location buffer, which is used to calculate the average, is filled with
the first value.
When the calibrator is installed, the value displayed in the message
should be the same as printed on the calibrator glass plate.
Give the following command:
>CHEC