9
UK
5 Function
5.1 Measuring principle
fig. 5-1
fig. 5-2
D
The unit operates to the principle of guided wave radar� It measures the level
using electromagnetic pulses in the nanosecond range�
The pulses are transmitted by the sensor head and guided along the rod (fig�
5-1)� When they hit the medium to be detected they are reflected and guided back
to the sensor (fig� 5-2)� The time between transmitting and receiving the pulse
directly relates to the travelled distance (D) and the current level� The reference for
distance measurement is the lower edge of the process connection�
The figures show operation with single probe� In case of operation with a
coaxial probe, the guided wave runs only along the inside of the coaxial
pipe�
