Chapter 3 ________________________________________________________________ Installation
VAISALA ________________________________________________________________________ 65
Background Luminance Options
FS11P can be fitted with one of two Background Luminance Sensor
options:
1 LM21 Background Luminance Sensor, for use in Runway Visual
Range (RVR) systems
2 Day/Night Photo Switch, for general nighttime meteorological
visibility
LM21 Background Luminance Sensor
The optional LM21 sensor offers the means for measuring ambient light
level or background luminance in RVR applications. The sensor is
mounted on the Sensor Arm, which is attached to the rear panel of the
radiation shield. The mechanical installation of LM21 and Sensor Arm is
shown in Figure 23 on page 48. Assembly instructions are described in
detail on pages 42 and 43, steps 15 and 16. The sensor should be directed
to face the North sky in the Northern hemisphere. Direct sunlight into the
sensor must also be avoided. The Background Luminance Sensor is
normally tilted at an angle of 20° to 50°. Generally, an installation angle
of 30° is recommended when there is no special reason to use a higher
one.
The Background Luminance Sensor is used for measuring the
background against which the pilot views the runway lights or runway
markings. A compromise must be made to achieve a measurement as
representative as possible and, on the other hand, to meet the installation
requirements. The luminance sensor must not face the runway lights
directly.
For detailed information of LM21 Background Luminance Sensor, see
the LM21 User's Guide. For system configuration, refer to section LM21
Background Luminance Sensor on page 99.
To Next Page
Loading...
