User's Manual

Page 124 SITRANS LR560 (mA/HART) – INSTRUCTION MANUAL 7ML19985KB01
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D: Technical Reference
Algorithm (2.7.3.1.)
The true echo is selected based on the setting for the Echo selection algorithm. For a list
of options see Algorithm (2.7.3.1.) on page 88.
Position Detect (2.7.3.3.)
The echo position detection algorithm determines which point on the echo will be used to
calculate the precise time of flight, and calculates the range using the calibrated
propagation velocity. The following options are available:
• Rising
• Center
•Hybrid
• CLEF (Constrained Leading Edge Fit)
Rising
Uses rising edge of the echo.
Center
Uses center of the echo.
Hybrid
Uses the Center algorithm for the top part of the vessel, and the CLEF algorithm for the
part nearest the vessel bottom, according to the settings for CLEF range.
CLEF (Constrained Leading Edge Fit)
• Uses the leading edge of the echo.
• Is used mainly to process the echo from materials with a low dK value.
In an almost empty flat-bottomed vessel, a low dK material may reflect an echo weaker
than the echo from the vessel bottom. The echo profile shows these echoes merging. The
device may then report a material level equal to or lower than empty
The CLEF algorithm enables the device to report the level correctly.