Micropilot S FMR 533
6 Commissioning
Hauser
57
6.5
Mounting calibration with VU 331
6.5.1
Function group "mounting calibr." (03)
Function "tank gauging" (030)
Using this function, you can either enter a dip table or carry out an auto-correction.
Function "auto correction" (031)
When measuring levels with radar systems, so-called "multipath reflections" can affect
the level signal giving rise to serious measuring errors. "Multipath reflections" also
include radar beams which are received by the radar system, which have not been
reflected directly by the medium surface. They may reach the antenna via the basin wall
and the medium surface. This phenomenon is particularly noticeable with devices
mounted near to walls, as soon as the conical radar beam strikes the basin wall.
The Micropilot S can automatically discover and correct measuring errors due to this
"multiple path" propagation. This is because it uses two independent sets of information
when evaluating reflection signals:
•
Firstly, it evaluates the
amplitude
of the reflected energy using the so-called envelope
curve system.
•
Secondly, it evaluates the
phase
of the reflected energy.
The decisive factor for a constant output signal is to assign the phase values to the
associated level values. This assignment is ensured using a correspondence table
(index correction table). The Micropilot S learns this for the specific application after
installation (learning period).
Therefore, after mounting the device, and
after
completing the basic calibration, a
history reset
must be performed (enter "
yes
" in the
"
history reset
"
(009)
function in the
"
basic setup
"
(00)
function group).
We advise you not to switch off the radar system during filling and emptying operations
during the teach-in phase. Switching off when there are only negligible level changes
produces no error.
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