Echo Lock; Echo Position Detection; Auto False Echo Suppression - Siemens sitrans LR200 Instruction Manual

Echo Lock

If the echo selected by Algorithm (2.2.3.1. 1 .) is within the Echo Lock window
is centered about the echo, which is used to derive the measurement. In radar
applications, two measurement verification options are used:
• Lock Off:
SITRANS LR200 responds immediately to a new selected echo (within the
restrictions set by the Maximum Fill / Empty Rate), but measurement reliability is
affected.
• Material Agitator:
A new measurement outside the Echo Lock Window must meet the sampling
criteria before the window will move to include it.
The other available options, Maximum Verification and Total Lock are not recommended
for radar.

Echo Position Detection

The echo position algorithm Position (2.2.3.1.3.) 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 (adjusted by a propagation factor, if necessary).
The options are Center or CLEF (Constrained Leading Edge Fit). CLEF uses the leading
edge of the echo. It can be used to compensate for materials with a low dK value, which
may cause the vessel bottom to be reported as the level instead of the actual material
level, in low level conditions. CLEF range is the level below which the CLEF algorithm will
be used: above this level the Center algorithm is used.
Hybrid uses a combination of Center and CLEF, depending on the setting for CLEF range.

Auto False Echo Suppression

If an obstruction is causing a large echo before the material level echo, that echo will rise
above the default TVT curve and may be selected as the true echo. Auto False-Echo
Suppression modifies the TVT curve so that the false echo will not rise above the TVT
curve.
When you use Auto False Echo Suppression, the device first learns the echo profile at
that moment. A learned TVT curve follows the echo profile and rises above the false
echo. You set Auto Suppression Range so that the learned profile replaces the default
TVT curve up to a point past the obstruction. From that point on, the default TVT curve is
used. The material level echo rises above this, and is selected as the true echo.
1)
See Echo Lock (2.2.3.2.1.)
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