Algorithm; Confidence; Echo Threshold - Siemens SITRANS LUT400 Operating Instructions Manual

Algorithm

The true echo is selected based on the setting for the Echo selection algorithm. For a list
of options see Algorithm (2.12.2. 1 .) on page 182. All algorithms ultimately use confidence
to select the true echo. However, when applications report a low confidence value, the
TR algorithm (which tracks the moving echo) can be used to predict the primary variable.
Algorithm
TF True First echo
TR TRacker
L Largest echo
Best of First and
BLF
Largest echo
Area, Largest,
ALF
and First

Confidence

Confidence (3.2.9.2.) describes the quality of an echo. Higher values represent higher
quality.

Echo Threshold

Echo Threshold (2.12.2.2.) defines the minimum confidence value required for an echo to
be accepted as valid and evaluated.
A5E33329501
Echo Determination
Selects the first echo that crosses TVT
curve.
Selects the echo that is closest to the
transducer, and is moving. (If echo loca-
tion is steady, BLF algorithm should be
used.)
Selects the largest echo above the TVT
curve.
Selects the echo (first and highest) with
the highest confidence value.
Selects the echo with the highest confi-
dence value based on the three criterion
(widest, highest, and first).
SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS
Suggested Usage
Use in liquids applica-
tions free of obstruc-
tions when confidence
of first echo is high.
Only use TR algorithm in
process applications
with continuous level
changes, and a risk of
fixed obstructions that
could interfere with true
level, resulting in low
confidence.
Use in long range liq-
uids applications with
large (tall) material
return echoes.
Default and most com-
monly used. Use in all
short to mid range gen-
eral liquids and solids
applications where there
is a relatively large (tall),
sharp echo.
Use in mid to long range
solids applications
where the material
return echo is wide and
large, and where com-
peting smaller echoes
challenge BLF.
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