Siemens SITRANS LUT400 Operating Instructions Manual page 296

Auto False Echo Suppression Range (2.12.3.2.) (Page 223) specifies the range within which
the learned TVT is applied. Default TVT is applied over the remainder of the range.
The material level should be below all known obstructions at the moment when Auto False
Echo Suppression learns the echo profile. Ideally the vessel should be empty or almost
empty.
The device learns the echo profile over the whole measurement range and the TVT is
shaped around all echoes present at that moment.
Auto False Echo Suppression Range must be set to a distance shorter than the distance to
the material level when the environment was learned, to avoid the material echo being
screened out.
Example before Auto False Echo Suppression
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Default TVT
False echo
Material echo
Sensor reference point
High calibration point = 1 m
Obstruction at 13 m
Material level at 31 m
Low calibration point = 45 m
Operating Instructions, 07/2019, A5E33329501-AC
SITRANS LUT400