Appendix A: Technical reference
A.2 Echo processing
SITRANS LR250 (PROFIBUS PA)
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Operating Instructions, 08/2014, A5E32221386-AC
Example after Auto False Echo Suppression
Auto False Echo
Suppression
Range set to 2 m
①
Learned TVT
④
Default TVT
②
False echo
⑤
Material echo
③
Auto False Echo Suppression Range
⑥
Echo marker
A.2.7
Measurement Range
Near Range (2.5.1.)
Near Range programs SITRANS LR250 to ignore the zone in front of the antenna. The default
blanking distance is 50 mm (1.97") from the end of the antenna.
Near Range allows you to increase the blanking value from its factory default. But Auto False
Echo Suppression (2.5.10.1.) is generally recommended in preference to extending the blanking
distance from factory values.
Far Range (2.5.2.)
Far Range can be used in applications where the base of the vessel is conical or parabolic. A
reliable echo may be available below the vessel empty distance, due to an indirect reflection
path.
Increasing Far Range to 30% or 40% can provide stable empty vessel readings.