User Manual VS2k-UMB / VS20k-UMB
V 2.3 / 28.01.2020
6
Chapter 4 Equipment description
4 Equipment description
The VS2k-UMB / VS20k-UMB is a visibility measurement device for the determination of
optical visibility in the range of 0
– 2000m / 0 – 20000m (32 – 6500 ft / 32 – 65617 ft), as
needed e.g. in the realm of environmental data acquisition in traffic management equipment.
4.1 Operation mode
Visibility is determined by measuring reflectance in accordance with the 42° forward
scattering principle
1
.
The particles in the field of measurement (e.g. fog droplets) scatter the infrared light emitted
by the transmitter. The receiver measures the rate of scattered light from which the
reflectance is calculated. Visibility is then computed taking account of the set border contrast.
The measurements are polled via the RS485 interface or transmitted as an analogue signal
via the current output.
The device is connected by means of an 8-pole screw-in connector using the associated
connection cable.
Windows PC software is available for configuration and measurement polling during
commissioning.
1
In a horizontal plane
