Siemens SITRANS LR250 Operating Instructions Manual page 239

Auto False Echo Suppression Range (2.5.10.2.)
Auto False Echo Suppression Range specifies the range within which the learned TVT is
applied. Default TVT is applied over the remainder of the range.
The learned TVT screens out the false echoes caused by obstructions. The default TVT allows
the material echo to rise above it.
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
①
②
③
④
SITRANS LR250 (PROFIBUS PA)
Operating Instructions, 08/2014, A5E32221386-AC
default TVT
false echo
material echo
sensor reference point
Appendix A: Technical reference
⑤
high calibration point = 0
⑥
obstruction at 1.3. m
⑦
material level at 3.2 m
A.2 Echo processing
237